refactor(pyamber): drop PyFilesystem2 for stdlib tempfile

[aglinxinyuan]

What changes were proposed in this PR?

fs (PyFilesystem2) is effectively EOL — 2.4.16 (2022) is the last release ever published, upstream still imports pkg_resources at import time, and setuptools 82 removed pkg_resources entirely, which is the sole reason amber pins setuptools==80.10.2 (#4199, #6412). ExecutorManager was the only consumer, and fs's TempFS is internally just tempfile.mkdtemp + shutil.rmtree, so the swap to stdlib is behavior-preserving.

Before:  ExecutorManager -> fs.open_fs("temp://") -> pkg_resources -> setuptools held < 82
After:   ExecutorManager -> tempfile.mkdtemp + shutil.rmtree -> fs gone -> setuptools unpinned

File	Change
executor_manager.py	fs.open_fs("temp://") → tempfile.mkdtemp(prefix="texera-udf-") + shutil.rmtree; property renamed fs → tmp_dir; lazy creation, sys.path handling, the never-materialized close guard, and the tolerated leak-on-force-kill semantics all preserved
test_executor_manager.py	the two direct manager.fs accesses use manager.tmp_dir; new non-ASCII UDF round-trip regression test (see below)
requirements.txt	drop fs==2.4.16 and the setuptools==80.10.2 pin — fs was the only distribution in the closure requiring setuptools (pytz's pkg_resources use is a guarded fallback)
LICENSE-binary-python	drop fs==2.4.16 and appdirs==1.4.4 (an fs-only transitive); six stays (python-dateutil needs it)
texera_run_python_worker.py, pyproject.toml	revert the #6880 warning filters — the warning's source is gone, so vs main these files are net-untouched (pyproject keeps only an EOF-newline fix)

One subtlety worth reviewer attention: fs's open() forced UTF-8 for text writes, while pathlib's open("w") uses the locale encoding — on a cp1252 Windows host, non-ASCII UDF code would crash at write time or fail at import (importlib decodes source as UTF-8 per PEP 3120). The swap therefore pins encoding="utf-8", newline="\n" explicitly, keeping byte-identical behavior with fs, and a regression test pins it.

Stacked on #6880 (contains its commit); whichever merges first works — if this one lands first, #6880 can simply be closed.

Any related issues, documentation, discussions?

Closes #6917.

How was this PR tested?

• New test_non_ascii_udf_source_round_trip written first: it fails with UnicodeEncodeError under a cp1252 locale without the explicit encoding="utf-8" (reproduced on Windows), and passes with it — pinning encoding parity with fs.
• The two close() branch tests were repointed at tmp_dir red-first (failing on the old attribute) before the source swap; all 23 test_executor_manager.py tests pass.
• Full pyamber unit suite from amber/: 750 passed, identical to the pre-change baseline apart from the added test (the handful of Iceberg-catalog failures on this Windows machine are identical on a clean tree). The suite's pkg_resources warnings disappeared at the source (5 → 1 total warnings) with no filter in place.
• Behavior parity was checked against fs's own implementation (fs/tempfs.py, fs/iotools.py): directory creation, close/cleanup semantics including double-close, and the cached-property guard translate 1:1.
• ruff check and ruff format --check pass on all touched files.

Was this PR authored or co-authored using generative AI tooling?

Generated-by: Claude Code (Fable 5)

[github-actions]

Automated Reviewer Suggestions

Based on the git blame history of the changed files, we recommend the following reviewers:

• Contributors with relevant context: @Ma77Ball, @Yicong-Huang
  You can notify them by mentioning @Ma77Ball, @Yicong-Huang in a comment.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 77.66%. Comparing base (429be11) to head (849a48c).
⚠️ Report is 19 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6928      +/-   ##
============================================
+ Coverage     77.31%   77.66%   +0.35%     
  Complexity     3524     3524              
============================================
  Files          1161     1161              
  Lines         45920    46043     +123     
  Branches       5099     5099              
============================================
+ Hits          35501    35760     +259     
+ Misses         8839     8703     -136     
  Partials       1580     1580              

Flag	Coverage Δ		*Carryforward flag
access-control-service	70.00% <ø> (ø)		Carriedforward from d13da15
agent-service	76.76% <ø> (ø)		Carriedforward from d13da15
amber	69.10% <ø> (ø)		Carriedforward from d13da15
computing-unit-managing-service	20.49% <ø> (ø)		Carriedforward from d13da15
config-service	66.66% <ø> (ø)		Carriedforward from d13da15
file-service	67.21% <ø> (ø)		Carriedforward from d13da15
frontend	82.58% <ø> (ø)		Carriedforward from d13da15
notebook-migration-service	78.94% <ø> (ø)		Carriedforward from d13da15
pyamber	95.38% <100.00%> (+3.23%)	⬆️
workflow-compiling-service	55.14% <ø> (ø)		Carriedforward from d13da15

*This pull request uses carry forward flags. Click here to find out more.

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[github-actions]

⚠️ Benchmark changes need a look

🟢 0 better · 🔴 2 worse · ⚪ 13 noise (<±5%) · 0 without baseline

Compared against main 49f9e2c benchmarked on this same runner, so the delta is largely free of cross-runner hardware noise. The "7d avg" column still reflects the gh-pages dashboard. Treat <±5% as noise unless repeated.

Dashboard · Run

	config	throughput	MB/s	latency	max Δ latest / 7d
🔴	bs=10 sw=10 sl=64	401	0.244	24,463/37,126/37,126 us	🔴 +11.4% / 🔴 +126.8%
⚪	bs=100 sw=10 sl=64	804	0.491	124,583/152,331/152,331 us	⚪ within ±5% / 🔴 +39.4%
⚪	bs=1000 sw=10 sl=64	911	0.556	1,093,537/1,177,616/1,177,616 us	⚪ within ±5% / 🔴 +12.1%

Baseline details

Latest main 49f9e2c from same runner

config	metric	PR	latest main	7d avg	Δ latest	Δ 7d
bs=10 sw=10 sl=64	throughput	401 tuples/sec	412 tuples/sec	759.72 tuples/sec	-2.7%	-47.2%
bs=10 sw=10 sl=64	MB/s	0.244 MB/s	0.251 MB/s	0.464 MB/s	-2.8%	-47.4%
bs=10 sw=10 sl=64	p50	24,463 us	24,037 us	12,653 us	+1.8%	+93.3%
bs=10 sw=10 sl=64	p95	37,126 us	33,336 us	16,371 us	+11.4%	+126.8%
bs=10 sw=10 sl=64	p99	37,126 us	33,336 us	19,941 us	+11.4%	+86.2%
bs=100 sw=10 sl=64	throughput	804 tuples/sec	817 tuples/sec	966.78 tuples/sec	-1.6%	-16.8%
bs=100 sw=10 sl=64	MB/s	0.491 MB/s	0.499 MB/s	0.59 MB/s	-1.6%	-16.8%
bs=100 sw=10 sl=64	p50	124,583 us	121,341 us	103,654 us	+2.7%	+20.2%
bs=100 sw=10 sl=64	p95	152,331 us	150,049 us	109,308 us	+1.5%	+39.4%
bs=100 sw=10 sl=64	p99	152,331 us	150,049 us	116,369 us	+1.5%	+30.9%
bs=1000 sw=10 sl=64	throughput	911 tuples/sec	913 tuples/sec	997.95 tuples/sec	-0.2%	-8.7%
bs=1000 sw=10 sl=64	MB/s	0.556 MB/s	0.557 MB/s	0.609 MB/s	-0.2%	-8.7%
bs=1000 sw=10 sl=64	p50	1,093,537 us	1,100,192 us	1,007,348 us	-0.6%	+8.6%
bs=1000 sw=10 sl=64	p95	1,177,616 us	1,137,155 us	1,050,149 us	+3.6%	+12.1%
bs=1000 sw=10 sl=64	p99	1,177,616 us	1,137,155 us	1,079,497 us	+3.6%	+9.1%

Raw CSV

config_idx,batch_size,schema_width,string_len,num_batches,total_ms,total_tuples,total_bytes,tuples_per_sec,mb_per_sec,lat_p50_us,lat_p95_us,lat_p99_us
0,10,10,64,20,499.27,200,128000,401,0.244,24462.71,37125.55,37125.55
1,100,10,64,20,2487.95,2000,1280000,804,0.491,124582.85,152331.17,152331.17
2,1000,10,64,20,21951.00,20000,12800000,911,0.556,1093537.15,1177616.10,1177616.10