Update NPMS to inform NMS of the changes in fw rules synchronously.

Currently, NPMS informs NMS synchronously at some events and
asynchronously at some others. If these sync and async calls get
interleaved, then NMS will end up in an inconsistent state.

In N-MR1, NPMS was updated to inform NMS asynchronously to avoid some
lock contentions during screen unlock. This shouldn't be a problem any more
since NPMS no longer updates its internal state on ui thread and also
netd calls have been optimized from ~50ms to ~7ms since then.

Bug: 66015813
Test: cts-tradefed run singleCommand cts-dev -m CtsHostsideNetworkTests -t \
      com.android.cts.net.HostsideRestrictBackgroundNetworkTests

Change-Id: I24ccb5819430f19014630e7b90cba1f0b993e430