Allow system to disable behavior of pausing animators for bg apps am: 161732cf

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18527682



Change-Id: Ib6e6b974b5524be77e7e2ce7f950f62ef0c5ea28
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>