Fix bluetooth state updated in systemui.

- Update both bluetooth and bluetooth connection state when bluetooth
state changes. This ensures that connection state is not stale when
bluetooth is turning off when establishing a connection.
- Display "Connecting..." when bluetooth is actively trying to establish
a connection instead of "Turning on..."

Change-Id: I16463f3f57c8adb6d9401fe478acaad5f987fa76
Fixes: 77528964
Test: runtest systemui