Update bluetooth summary text when state changes.

- Refresh connected state before setting summary text.
- Detect inconsistent state (BT manager says connected but doesn't
  provide a connected device)

(This basically syncs implementation between settings and QS tile)

Change-Id: Id23138f8432b9aecd194f5016bf2576e33e8ca98
Fixes: 33341275
Test: RunSettingsRoboTests