[audio] Deprecate/rename mute event for clarity

With multiple op mute sources, rename MUTED_BY_APP_OPS to
MUTED_BY_OP_PLAY_AUDIO for clarity. Set to same value and deprecate the
latter.

Test: Compiles
Flag: EXEMPT safe
Bug: 380329395
Change-Id: Id4d196aeed96e3e89dbd978e8e57153bc027a390