Remove callback upon MediaSession#release am: 3cfa79c53c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/24464032

Change-Id: Id5d88ffe719ab629d4393cf9e912e4708a33cf19
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>