Remove legacy callback interfaces

Remove interfaces associated with the legacy callback interface.
Note, some dead code in AudioTrack cannot be removed due to dependence
of vendor code on link time (b/169889714).

Test: Compiles, modified tests pass
Bug: 199156212
Merged-In: I544613e61b6879c188ee6aafdc3bdbabac3cc064
Change-Id: I544613e61b6879c188ee6aafdc3bdbabac3cc064
11 files changed