Use hasBeenResumed() for checking if launcher is resumed

ag/23852178 introduced a clean up for launcher state when invoking
transient taskbar. It was checking launcher activity resumed state with
`isResumed()` method. This breaks transient taskbar for desktop mode as
we are marking the launcher activity to be paused using the launcher
flags. `hasBeenResumed()` method is the one we can used instead as it is
checking the launcher flags and not the resumed state of the activity
itself.

Bug: 292266259
Test: open transparent activity on top of launcher
      unstash taskbar
      go home
Test: move an app to desktop, unstash taskbar
Change-Id: I98d14dbfdde4b857f50e62206fc0f308e8f54231