[Flag cleanup] edit_shortcuts_in_full_screen is always on now

- Cleaned up the code that won't be executed when the flag is on
- Remove unused resources

Bug: 300302098
Test: Manually verify the user can change the shortcut type, and the
changes are saved
Test: atest com.android.settings.accessibility
Flag: EXEMPT removing com.android.settings.accessibility.edit_shortcuts_in_full_screen

Change-Id: I1e32b724ca3da909feda55e20fb1d51dc4680c09