Drop unnecessary system menu match from apps_menu_button

This goes back to when we called this needle desktop_clean, but
there's really no point in having it.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/gnome/apps_menu_button-20190625.json

@@ -1,18 +1,11 @@
 {
     "area": [
         {
-      "type": "match",
             "height": 15,
-      "ypos": 7,
-      "width": 67,
-      "xpos": 9
-    },
-    {
             "type": "match",
-      "xpos": 968,
-      "height": 18,
-      "ypos": 4,
-      "width": 43
+            "width": 67,
+            "xpos": 9,
+            "ypos": 7
         }
     ],
     "properties": [],