Fix issue where location provider overlay may not bind

Using a default backup provider build into the system that will be
used as last priority. Guards against many cases of user location
not being available when the overlay app is misbehaving.

Bug: 325028454
Test: atest GnssOverlayLocationServiceTest, manual
Change-Id: I6f357c9b0fcc19d56f80119a4fd358260f89b057