feat(release): Remove release-bubbles-ui feature flag (#93728)

The `organizations:release-bubbles-ui` feature flag registration was
removed from `sentry/src/sentry/features/temporary.py`. This change was
made as the feature is fully released and the flag is no longer needed.

---------

Co-authored-by: Cursor Agent <[email protected]>

Author: billyvg

src/sentry/features/temporary.py

@@ -303,8 +303,6 @@ def register_temporary_features(manager: FeatureManager):
     manager.add("organizations:related-issues", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable the release details performance section
     manager.add("organizations:release-comparison-performance", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
-    # Enable the new release bubbles UI on charts
-    manager.add("organizations:release-bubbles-ui", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable replay AI summaries
     manager.add("organizations:replay-ai-summaries", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enable version 2 of reprocessing (completely distinct from v1)