Use the fast track for the AppCollector.

This replaces some of the threading shenanigans done to get this
working with the regular PackageManager call. By swapping this
out, we can get results faster, using less power, and with a
simpler implementation and testing strategy.

Bug: 35807386
Test: FrameworkServicesTest
Change-Id: Ib94fd7eba838b5e728f8f2615bcb4d9c82f21885