Send VPN manager event when VPN always-on status is changed am: 52f9de42 am: 8ababe76

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18112116



Change-Id: I3054d1f3b0b60c4d8315724304ebfd70940b46be
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>