LockSettingsStorage: don't ignore insertion exceptions

There have been reports of data going missing from the locksettings
database.  While these are likely to have another cause, we should rule
out insertion errors by ensuring they cause an exception to be thrown.

Bug: 367405456
Test: atest FrameworksServicesTests:com.android.server.locksettings
Flag: EXEMPT bugfix
Change-Id: Ic144446831db79418abd4165a56c472fa3a0f3ac