Backport finalizer fixes to release-v1.41

[caseydavenport]

Backports the remaining finalizer fix that addresses flaky test failures:

• Fix finalizer race between whisker and goldmane controllers #4492 — Switch finalizer patching to MergeFromWithOptimisticLock to fix a race between whisker and goldmane controllers where concurrent patches silently clobbered each other. Also wraps the whisker FV test finalizer creation assertion in Eventually to handle the race.