Merge "Unify the verification for unregister a NetworkAgent" am: 14e14a36ea am: 65fd62fc63 am: 158fae71b4

Original change: https://android-review.googlesource.com/c/platform/packages/modules/Connectivity/+/1664603

Change-Id: I97ee3029dabb089588c3dabf36733f83d5628d56