UX: move "hide profile" checkbox to profile tab (#31095)

This moves the "hide my public profile" checkbox from the
/my/preferences/interface > other section into the top of the
/my/preferences/profile section.

Internal ref - t/146570

spec/system/page_objects/pages/user_preferences_profile.rb

@@ -8,6 +8,14 @@ module PageObjects
         self
       end
 
+      def hide_profile
+        find(".user-hide-profile .pref-hide-profile").click
+      end
+
+      def has_hidden_profile?
+        has_css?(".user-hide-profile .pref-hide-profile input[type=checkbox]:checked")
+      end
+
       def expand_profile_details
         find(".user-main .details .controls .btn-default").click
       end