Merge "Add unit test for NetworkStatsSubscriptionsMonitor" into rvc-dev am: 32f8a56636 am: 7a65307e4f am: b710136e56

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

Change-Id: I48486d88ee3fa4b81af8e82203d2810f118be7c2