Fix issue with rebind to dialer on uninstall of app.

Fixed issue where uninstall of a random app while not in car mode would
cause the dialer to disconnect and rebind.

Test: Manually tested by uninstalling an unrelated app and seeing
the problem manifest itself.  Applied fix and verified it no longer causes
a problem.
Test: Manually uninstalled active car mode app and ensured fallback to
dialer UX.
Test: Added two new unit tests for this.
Fixes: 174697155

Change-Id: Icd325615dd13ca622c0004d88c2c4b7c57b4152f