Fix clicking the allow/deny button of the dialog was not working after quickly...

Fix clicking the allow/deny button of the dialog was not working after quickly clicking multiple times.

Root cause:
Show at least two dialogs after quickly clicking multiple times.

Goal:
Should only show one dialog on the screen.

Bug: 233248607
Test: atest AccessibilityShortcutChooserActivityTest
Change-Id: I7dcc9708fe1fe178017464b09e8aa8abaa6a07ac