Add a config to control if show the prompt on abusive apps

And turn it OFF by default, will turn it ON in teamfood now.

Also move the alert threshold to 4% again.

Bug: 203105544
Test: atest FrameworksMockingServicesTests:BackgroundRestrictionTest
Change-Id: Iff485b1795c9cf4e5ade847a8dac6a223c3bfd65