Merge "Add unit test for NetworkStatsSubscriptionsMonitor" into rvc-dev am: 32f8a56636 am: 7a65307e4f am: 2acbd72f5e

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11788484

Change-Id: I643f27dda377ee5d2fa885cac8b814445363a20d