Add VPN app into power saver whitelist for a while to start its service am: 4b776c64

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/18699675



Change-Id: I5311e031b4e340554f82457c85d944226f755ad3
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>