Updated the SET_DEFAULT_ACCOUNT_FOR_CONTACTS's permission protection

level to knownSigner.

Bug: 378012462
Test: Tested on device
Flag: android.provider.new_default_account_api_enabled

	modified:   res/AndroidManifest.xml
	modified:   res/res/values/config.xml

Change-Id: I618ebb3debd5cc2422111190392531f8f42edf96