Don't enforce max tasks in KeyboardQuickSwitchView

The number of tasks to show should not be limited when KQS gets shown in
desktop windowing - instead of enforcing the limit on tasks shown in the
KQS view itself, trust the KeyboardQuickSwitchController to pass in
correctly sized list of tasks to show (KeyboardQuickSwitchController
does limit the task list size passed to the view).

Bug: 374329990
Test: Open 6+ tasks in fullscreen, and in desktop windowing. Verify that
the number of tasks shown in KQS is limited to 6 when shown from a
fullscreen app context, and not limited when shown when in desktop
windowing.
Flag: EXEMPT  bugfix

Change-Id: I245d05239f2fc025ef40085aff4bece694e0f76c