Allow s_noise override to actually be used

[catboxanon]

Description

Closes #8501

This fixes a regression introduced all the way back in October by #3040 where s_noise was set to 1 in the function definition, so the option in settings was no longer read. Because the value could be anything inclusive between 0 and 1 it should just read from the options directly.

Checklist:

• I have read contributing wiki page
• I have performed a self-review of my own code
• My code follows the style guidelines
• My code passes tests

[AUTOMATIC1111]

The intention was that Processing's args override options, so the way to fix the bug while preserving the original intent would be to self.s_noise = s_noise if s_noise is not None else opts.data.get('s_noise', 1.0), and to set default value for s_noise in constructor to None.

[catboxanon]

Done.

[AUTOMATIC1111]

Also opts.data.get('s_noise', 1.0) should be just opts.s_noise.