Applying OEM network pref to all users

Updating handleSetOemNetworkPreference so that the given policy is
applied to all users on the device. Additionally, remove uids for all
users/apps so that stale uids don't stay present after rematch. Finally,
small cleanup on how we deal with remote exceptions.

Bug: 181581017
Bug: 176494815
Test: atest FrameworksNetTests
atest NetworkStackTests
atest FrameworksNetIntegrationTests
atest NetworkStackIntegrationTests
atest CtsNetTestCasesLatestSdk

Change-Id: I214717ee0c78cfe8322e551c2c2e9dc01c0242b2