WifiConfigStore: Limit integrity checks to single user devices

Bug: 138482990
Test: atest com.android.server.wifi
Test: Device boots up & verified that config store files are not
integrity protected.
Test: Will send for full wifi regression tests.

Change-Id: I1bf8ae320935cc1bf70625792c4c1a5e0d54f034
Merged-In: I1bf8ae320935cc1bf70625792c4c1a5e0d54f034
5 files changed