Branching Taskbar visible/hidden assertion from testQuickSwitchToPreviousAppForTablet

- There seems to be test corruption that is coming from the TwoPanelWorkspaceTest as they are getting marked ignored from assumption exception.

- We are branching the logic of asseting taskbar depending on taskbar variant until we figure out how we can run test with TaskbarSwitchMode test annotation and pass it on first attempt. This is cunrrently not working for above reason.

Test: Presubmit
Bug: 286084688
Flag: not needed
Change-Id: I77a141455eceffd11fa8f74a7e204de9b36384fd