Allows the a11y volume shortcut disambig dialog to show on lock screen.

The edit button is not shown when the dialog is triggerred while on the
lock screen, to prevent editing shortcuts while the device is locked.

Bug: 303871725
Test: Set up 2+ features with volume key shortcut. Press power button to
      go to lockscreen. Trigger the volume key shortcut. Observe dialog
      appears without edit option.
Test: atest AccessibilityShortcutChooserActivityTest
Change-Id: Ia2ec0f9d01ffff0d51d23b491d55ef84d575f09d