Merge changes Ic5750d4f,I9fa888c9,I4211475f

* changes:
  Deflake testNetworkBlockedStatusAlwaysOnVpn
  Simplify testVpnRestrictedUsers.
  Add test coverage for LockdownVpnTracker.
tree: bfce05900d4a0e077d30967814d81d9c6c6f087e
  1. core/
  2. service/
  3. services/
  4. tests/
  5. OWNERS