Removes overrides for shortcut-required service toggling.

These are unnecessary now that shortcut enabling is done via
A11yManager#enableShortcutsForTargets which handles enabling
a shortcut-required service if necessary, controlled by the
rolled out a11yQsShortcut flag.

These also cause a race condition conflict when attempting to toggle a
service that does not require a warning, causing it to disable the
service immediately after enabling.

Bug: 324653372
Flag: android.view.accessibility.a11y_qs_shortcut
Test: Toggle a shortcut-required service that does not require
      a warning; service is started correctly.
Test: Repeat for a service that does require a warning
Change-Id: Iff44d87faf8a5d2eb9b6643dd582c2b697ad0b5d