Fix Taskbar being visible over Hotseat when recreated in Overview

Debugging locally, it seems there were a couple of state changes
and the last one (which is correct) was getting clobbered by a
previously destroyed instance of TaskbarLauncherStateController.
Fixed this by updating the isDestroyed() call which previously
only checked TaskbarActivityContext to now check
TaskbarLauncherStateController's destroyed state directly. This
is needed because TaskbarLauncherStateController is part of
LauncherTaskbarUIController which can be destroyed independently
of the other Taskbar controllers when Launcher is destroyed.

Also fix a debug log that was not updated long ago in ag/21122190

Flag: EXEMPT bugfix
Test: Go to overview, change Font Scale or Dark Theme from Quick
settings, ensure Taskbar is not visible over Hotseat
Fixes: 302923055

Change-Id: I1299462955b51a2bf931f022177045b1cec039c5