Locale selection settings do not hide warning dialog.

Locale selection settings do not hide warning dialog.

1. If there is more than one user on the device and a user tries
   to modify the locale which is shared across all users we are
   showing a warning dialog. When the user selects OK we are
   changing the locale and going to the previous screen. This is
   achieved by removing the locale selection fragment from the
   backstack. The problem was that the dialog was not dismissed
   upon OK in the dialog which resulted in saving the dialog's
   state and an attempt to restore it on the wrong fragment which
   has no idea about this dialog, this returning a null dialog
   resulting in a crash. This change removes the dialog on
   OK selection.

bug:7265186

Change-Id: I336ab54f5281c7a9ae24f1c25769daac46477ebd