Fix incorrect app count displayed under special app access

- This special app Google Play services will change its hasLauncherEntry
  value after receiving the MSG_LOAD_LAUNCHER.
- Update the summary while SpecialAppAccessPreferenceController is
  receiving the onLauncherInfoChanged callback.

Fixes: 150480524
Test: manual test
Change-Id: I26b99fce54606644ee5603b4ca4730267c0f7ce5