Drop skip_button needle

It was only used by a bit of gnome-initial-setup handling that
was removed as we no longer use it since F39 went EOL.

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

needles/gnome/skip_button-bold-20220817.json

@@ -1,16 +0,0 @@
-{
-  "area": [
-    {
-      "width": 32,
-      "ypos": 46,
-      "height": 21,
-      "xpos": 970,
-      "type": "match"
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "skip_button",
-    "LANGUAGE-english"
-  ]
-}

needles/gnome/skip_button-bold-20230701.json

@@ -1,16 +0,0 @@
-{
-  "area": [
-    {
-      "xpos": 970,
-      "width": 32,
-      "type": "match",
-      "height": 21,
-      "ypos": 46
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "skip_button",
-    "LANGUAGE-english"
-  ]
-}