Batch calls to the Metadata Syncer

Context: Sometimes we can have consecutive calls requesting a sync, originating from a single batch of updates.
Flag: android.app.appfunctions.flags.enable_app_function_manager
Test: atest FrameworksAppFunctionsTests -c + cts
Bug: 357551503
Change-Id: Ib895fa87efbd92e83d547ed0d745e424d6aa1e32