Drop a no-longer-needed needle

This was used by one of the workarounds we dropped recently. CI
was broken so I missed this.

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

needles/anaconda/install_process/anaconda_grey_stuck-20241130.json

@@ -1,15 +0,0 @@
-{
-  "area": [
-    {
-      "xpos": 9,
-      "ypos": 9,
-      "width": 1003,
-      "height": 745,
-      "type": "match"
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "anaconda_grey_stuck"
-  ]
-}