[Action Corner] Only check lockscreen visibility when device is connected

Checking lockscreenVisibility when device is not connected is not necessary and would cause perf regression.
It is a cold flow and should only be called when device is connected.

Bug: 431230605
Test: ActionCornerRepositoryTest
Test: ActionCornerInteractorTest
Flag: com.android.systemui.shared.cursor_hot_corner
Change-Id: Ie46ea4b1b25956a18bd66579a4fdec3a03b6c628