Show highlight around the selected overview tile

Enable highlight around focused overview item when desktop windowing
prototypes are enabled.
This highlight was built for and enabled with keyboard quickswitch feature.
We don't support quickswitch on desktop yet.
Disable the quickswitch, but keep the border highlight.

Bug: 269342116
Test: enable desktop windowing proto, use an external keyboard and
  alt+tab to switch between apps, observe highlight in overview, no
  quickswitch popup
Test: enable desktop windowing proto, enable
  ENABLE_KEYBOARD_QUICK_SWITCH, observe that alt+tab still opens
  overview
Test: disable desktop windowing proto, enable
  ENABLE_KEYBOARD_QUICK_SWITCH, observe alt+tab opens the quickswitch
  popup, and highlights in overview
Change-Id: I15b36f082610f4ce38143856c84fef723f1b8ba0