AVRCP: increase log info density

AVRCP has a lot of log messages that have little to no info.
Particularly with carkits that poll for data all the time, this makes it hard
to debug anything.

Remove logs where there's no info, add info where it's available with the goal
of making every log message useful.

Remove variables that we don't use anymore.

Print Now Playing Queue data on the dumpsys and when we report it
back to the controller.

Test: connect to a carkit and grab a bugreport
Bug: 37707672
Bug: 36802046
Bug: 38264897
Change-Id: I4fcb5a1c625c2d212685b4df04a0ac42df3d7841
(cherry picked from commit e5384f02)