xpay: fakenet test: move funds when payment succeeds

[Lagrang3]

Improved the fakenet simulation by moving funds after a payment succeeds. This triggers a bug in xpay.

To-do:

• fix the 1msat xpay bug that fails the test_xpay_fake_channeld

[Lagrang3]

This is an extract of the logs

...
PAYING Node #0
PAYING Node #1
PAYING Node #2
PAYING Node #3
PAYING Node #4
PAYING Node #5
PAYING Node #6
PAYING Node #7
PAYING Node #8
...
        for n in range(0, 9):
            if n in canned_gossmap_badnodes:
                continue
    
            print(f"PAYING Node #{n}")
    
            preimage_hex = bytes([n]).hex() + '00' * 31
            hash_hex = sha256(bytes.fromhex(preimage_hex)).hexdigest()
            inv = subprocess.check_output(["devtools/bolt11-cli",
                                           "encode",
                                           n.to_bytes(length=8, byteorder=sys.byteorder).hex() + '01' * 24,
                                           f"currency={chainparams['bip173_prefix']}",
                                           f"p={hash_hex}",
                                           f"s={'00' * 32}",
                                           "9=020000",  # option_basic_mpp
                                           f"d=Paying node {n}",
                                           f"amount={AMOUNT}msat"]).decode('utf-8').strip()
            assert l1.rpc.decode(inv)['payee'] == nodeids[n]
>           failed_parts.append(l1.rpc.xpay(inv)['failed_parts'])
...
>           raise RpcError(method, payload, resp['error'])
E           pyln.client.lightning.RpcError: RPC call failed: method: xpay, payload: {'invstring': 'lnbcrt5m1p4yhz30sp5qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqpp5qe7ud2qsrqlfq60k8sszpd5jcy3v34vzv0kh7hqw2v2sfhpmdcrqdq42pshj6twvusxummyv5srscqpj9qyyqqqzmuns0mernvj9rzhsa07vh8p87rmrywxk6744wsjjxsu8x5j5vq4zaharev330qc9k3qgderuw8xh8phykajy8nwkl9ve83f4weau7sqd7675n'},
error: {'code': 209, 'message': "Timed out after after 842 attempts.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102199msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102197msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102196msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102195msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102194msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102193msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102192msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102191msat.
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198102190msat
...
We got temporary_channel_failure for 45210x2134x44171/0, assuming it can't carry 198101779msat.
Payment of 9996982msat reached destination, but timed out before the rest arrived..
Payment of 998000msat reached destination, but timed out before the rest arrived..
Payment of 3000000msat reached destination, but timed out before the rest arrived..
Payment of 197000000msat reached destination, but timed out before the rest arrived..
Payment of 91005018msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived.. 
...
Payment of 1msat reached destination, but timed out before the rest arrived..
Payment of 1msat reached destination, but timed out before the rest arrived.. "}