Don't check record.isActive() to determine if a session is engaged

This isActive flag is only used to publish sessions to other parts
of the system and says nothing about whether the session is actively
being used for playback.

Bug: 417853575
Flag: com.android.media.flags.enable_notifying_activity_manager_with_media_session_status_change
Test: ActivityManagerNotifyMediaFGSTypeTest
Change-Id: I193761ea45bc1827edd7cd023cec323e907bbd93