Use accessibilityManager#enableShortcutsForTargets when turning shorcuts off/on

Replaces known instances where optIn/OutValueToSettings is used,
or settings are modified directly to add/remove a target to/from a shortcut.

Most instances where shortcut target settings are cleared,
or set to a default value (usually in tests), have not been altered

Bug: 332006721
Test: run atest for modified classes
Flag: aconfig android.view.accessibility.a11y_qs_shortcut ENABLED
Change-Id: I7c9c6733c289c382565cc212db2cc4361a1a05dd