Expose enable_sse_entry_point_updates through /api/configuration

The frontend entryPointStore reads this flag from configStore to pick
between SSE and polling. Without the allowlist entry, the key is never
serialized to the client, so even when operators set it to true the
browser sees undefined and falls back to the polling branch.

Author: mvdbeek

lib/galaxy/managers/configuration.py

@@ -230,6 +230,7 @@ def _config_is_truthy(item, key, **context):
             "tool_training_recommendations_api_url": _use_config,
             "enable_notification_system": _use_config,
             "enable_sse_history_updates": _use_config,
+            "enable_sse_entry_point_updates": _use_config,
             "instance_resource_url": _use_config,
             "instance_access_url": _use_config,
             "organization_name": _use_config,