chore(seer grouping): Remove metadata flag and killswitch (#75016)

This removes the `projects:similarity-embeddings-metadata` flag, which we no longer use[1] and whose feature handler has also been removed[2], and the `seer.similarity-embeddings-metadata-killswitch.enabled` option, which we've never actually used.

[1] #74914
[2] getsentry/getsentry#14743

Author: lobsterkatie

src/sentry/features/temporary.py

@@ -524,8 +524,6 @@ def register_temporary_features(manager: FeatureManager):
     manager.add("projects:similarity-embeddings-delete-by-hash", ProjectFeature, FeatureHandlerStrategy.OPTIONS, api_expose=False)
     # Enable similarity embeddings grouping
     manager.add("projects:similarity-embeddings-grouping", ProjectFeature, FeatureHandlerStrategy.INTERNAL, default=False, api_expose=False)
-    # Enable adding seer grouping metadata to new groups
-    manager.add("projects:similarity-embeddings-metadata", ProjectFeature, FeatureHandlerStrategy.INTERNAL, default=False, api_expose=False)
     manager.add("projects:similarity-indexing", ProjectFeature, FeatureHandlerStrategy.INTERNAL, api_expose=False)
     manager.add("projects:similarity-view", ProjectFeature, FeatureHandlerStrategy.INTERNAL, api_expose=True)
     # Starfish: extract metrics from the spans

src/sentry/options/defaults.py

@@ -842,12 +842,6 @@
     type=Bool,
     flags=FLAG_MODIFIABLE_BOOL | FLAG_AUTOMATOR_MODIFIABLE,
 )
-register(
-    "seer.similarity-embeddings-metadata-killswitch.enabled",
-    default=False,
-    type=Bool,
-    flags=FLAG_MODIFIABLE_BOOL | FLAG_AUTOMATOR_MODIFIABLE,
-)
 register(
     "seer.similarity-embeddings-delete-by-hash-killswitch.enabled",
     default=False,