Add Log.wtf when transports are missing

Because onCapabilitiesChanged will always be called, transports should
always exist in the map. If the transports are missing, error should be
report through Log.wtf.

Bug: 282587998
Test: atest MdnsSocketProviderTest
Change-Id: Ie2a93217542bfa6ee30bf3b9f73eb4ae8473fd09
1 file changed