[Large screen] Show full screen CreateShortcutActivity

Show full screen for CreateShortcutActivity because

-Launcher startActivityForResult for Intent.ACTION_CREATE_SHORTCUT and
 activity stack starts from launcher, CreateShortcutActivity will not
 follows SplitPaitRule registered by Settings.

- There is no CreateShortcutActivity entry point from Settings app UI.

Bug: 200916507
Test: manual
      Launcher menu ->  Widgets -> Settings -> select an item.
      Observe if it goes back go launcher.
Change-Id: I437ff9b82d5a4548e10aed7bd083fd01352433f4