Use active/inactive fgs calls instead of delegate.

Changes in this commit replaces fgs delegate with media specific
active/inactive calls.

Flag: com.android.media.flags.enable_notifying_activity_manager_with_media_session_status_change
BUG: 281762171
Test: launch app with steps -
a. launching spotify app
b. play a song.
c. pressing home
d. pause, wait for 30sec, then play, pause, play before 30 sec timeout
e. combination of step d.

watch-uid output can be found here:
https://paste.googleplex.com/4869785971326976
output from media session service can be found here:
https://paste.googleplex.com/4869785971326976



Change-Id: I2232201a5aa7da9f1b8ccab4bc29d1e53f573846
Signed-off-by: Pradeep Sawlani <sawlani@google.com>