Do not preserve settings changed by 'android' package

Bug: 144838882
Test: atest SettingsProviderTest:SettingsStateTest

System reinitialises some settings to the same value after reboot (e.g.
bluetooth_on, accessibility_enabled, font_scale). Such modifications
shouldn't set isPreserved flag.

Change-Id: Ib929bf7d544b78202691eff3ae2ac75f2c209aa2