feat: simplify and speedup feature_governance.py test by generating less blocks

[knst]

Issue being fixed or feature implemented

Too many blocks are generated in a functional tests feature_governance.py

What was done?

1. Activate v20 faster for feature_governance.py, drop generation of useless blocks, simplify code.

2. Added extra logging for this test by converting comments to logs.

How Has This Been Tested?

Run test/functional/feature_governance.py
Locally improvement of performance is less than 5 seconds.
tsan jobs on CI:

204/264 - feature_governance.py --legacy-wallet passed, Duration: 243 s
208/264 - feature_governance.py --descriptors passed, Duration: 270 s

↑ old version vs new version ↓:

193/264 - feature_governance.py --legacy-wallet passed, Duration: 220 s
199/264 - feature_governance.py --descriptors passed, Duration: 240 s

Most of the time is spent in feature_governance.py on stage "let all fulfilled requests expire for re-sync to work correctly" so that's a very minor optimization.

Breaking Changes

N/A

Checklist:

• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have added or updated relevant unit/integration/functional/e2e tests
• I have made corresponding changes to the documentation
• I have assigned this pull request to a milestone

[UdjinM6]

utACK 42dffe8

[PastaPastaPasta]

utACK 42dffe8