python: changes in google-cloud-service-management tests

[jskeet]

packages/google-cloud-service-management/tests/unit/gapic/servicemanagement_v1/test_service_manager.py has changes in googleapis/google-cloud-python#16584 which I don't understand.

We can add it to the "skip generate to start with" list but need to figure out what's different.

[jskeet]

I've found that explicitly regenerating this with legacylibrarian creates the same code - so this is a false positive, effectively. (Running "legacylibrarian generate" without any changes in the protos themselves skips regenerating.) It's potentially a bug in legacylibrarian from the last time the image was updated, but I'm not going to dig into that.

I'll leave this open until it's confirmed that there's no reason not to take the change.

[jskeet]

Note: this does not block migration; it should be resolved as part of the migration itself.

[jskeet]

The migration PR has been approved, so this is fine.