[SettingsProvider] update per-package memory usage on clearAppData

When clearAppData is called, the system settings inserted by this app
will be deleted. We should update the per-package memory usage for this
app accordingly so that the app can continue to insert more system
settings.

Flag: EXEMPT bugfix

BUG: 346461144
Test: atest com.android.providers.settings.SettingsStateTest#testMemoryUsagePerPackage_StatsUpdatedOnAppDataCleared

Change-Id: I16cbd08cbd137725db50737e81d181d89e0a1a69