[automerge] Revert "Enable media session flag by default" 2p: 0d717c5199 2p: 49e269f545

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17689977

Change-Id: I5ef1293adb24efc6cc4af5ef6566a9d73230bc19