feat(dynamic-sampling): add feature flag (#79084)

Author: constantinius

Diff for: src/sentry/features/temporary.py

@@ -123,6 +123,8 @@ def register_temporary_features(manager: FeatureManager):
     manager.add("organizations:discover", OrganizationFeature, FeatureHandlerStrategy.INTERNAL, api_expose=True)
     # Enable the org recalibration
     manager.add("organizations:ds-org-recalibration", OrganizationFeature, FeatureHandlerStrategy.INTERNAL, api_expose=False)
+    # Enable custom dynamic sampling rates
+    manager.add("organizations:dynamic-sampling-custom", OrganizationFeature, FeatureHandlerStrategy.FLAGPOLE, api_expose=True)
     # Enables data secrecy mode
     manager.add("organizations:enterprise-data-secrecy", OrganizationFeature, FeatureHandlerStrategy.INTERNAL, api_expose=False)
     # Enable issue platform deletion