Fix a race when removing from LegacyTypeTracker.

Because LegacyTypeTracker#remove can send broadcasts that cause
apps to refresh their view of network state, it needs to be
called only after network state has been updated. This requires
that callers determine whether the network was the default, and
updating state, before calling remove().

While I'm at it, fix maybeLogBroadcast's concept of whether the
network it's logging about is/was the default. This has never
been correct.

Bug: 20613953
Change-Id: Ia175ac454aa4e0a4c4f0151866314ebada681438