Allow system to disable behavior of pausing animators for bg apps am: 161732cf am: b67d9848

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



Change-Id: I89c55511b222db569d5ceee292348ad6f0359839
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>