Restricting Accessibility flows for Private Profile.

Adding PS apps to the home screen is restricted.
This CL prevents the same from accessibility drags.

Bug: 289223923
Flag: ACONFIG com.android.launcher3.Flags.private_space_restrict_accessibility_drag DEVELOPEMENT
Test: Ran Launcher3 Tests.
Change-Id: I3e2b7b196b96a4d2ba34d8ece5fd6e0463f17253