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

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

Change-Id: Ib59bb377f7ef5f229e8e1bd692e95d57998620f5