Fix MCP config priority logic in sessions.py (#9237)

Co-authored-by: openhands <openhands@all-hands.dev>
Co-authored-by: Engel Nyst <enyst@users.noreply.github.com>

openhands/server/user_auth/default_user_auth.py

@@ -52,6 +52,11 @@ class DefaultUserAuth(UserAuth):
             return settings
         settings_store = await self.get_user_settings_store()
         settings = await settings_store.load()
+
+        # Merge config.toml settings with stored settings
+        if settings:
+            settings = settings.merge_with_config_settings()
+
         self._settings = settings
         return settings