Added a config for the killswitch to disable account restriction in Contacts Provider.

Bug: 357887663
Test: atest ContactsProviderTest
Flag: android.provider.new_default_account_api_enabled

	modified:   core/res/res/values/config.xml
	modified:   core/res/res/values/symbols.xml

Change-Id: Ifa3ad1e4f563dddb458973da9ad2c3d3bbd18398