Merge changes from topic "revert-3561690-revert-3538339-SNUWWZJNJZ-BUWEOGUTIT" into main

* changes:
  Add TargetApi annotation to ConnectivityService and QuicConnectionCloser
  Revert "Revert "Remove unnecessary ifindex arg from destroyUdpSo..."
  Revert "Revert "Add hidden API to register/unregister QUIC conne..."