Show mic access as background for emergency app

It is believed that the user will be confused if they see that the app
is only requesting microphone access in the foreground. This is just a
UI change and the app actually never has access in the backgorund.

Test: Carcrash onboarding flow
Bug: 160718710
Change-Id: I97fcdea178b86231a3de74da6c3023514a896395