Temporary additional logging to investigate bug

The bug appears related to continuing to use an invalid buffer provider
in fast mixer after track destruction, so focus the added logs in that area.

Also includes a bug fix: was calling log in an unsafe place
near Threads.cpp AudioFlinger::PlaybackThread::createTrack_l line 1250.

Details:
 - include caller pid or client pid where appropriate
 - increase log buffer size
 - log mFastIndex when AudioMixer sees an invalid bufferProvider.
 - log both potentially modified and actually modified tracks in FastMixer.
 - fix benign bug where sq->end() was called more than once.
 - log StateQueue push() call and return.

Bug: 6490974
Change-Id: Iee7c8f40e20b6000cd8286c0ec6a14fff4a37af1