[NS A13] Move legacy broadcast handling after rematch.

As opposed to other patches in this series, there is a logic change
here. This will send all necessary legacy broadcasts after all
matches have been done.

This should be fine because the callbacks and the broadcasts are
unordered anyway, and the broadcasts are still sent in the same
order as before ; there should not be an observable change from
apps besides some jitter.

Bug: 113554781
Test: ConnectivityServiceTest
Change-Id: Ibeab8d0a9106c5198228888ac33084238c0a4a1a