ci(renovate): Group all rook-ceph related updates

This patch should group up the rook operator and cluster updates into one
Merge Requests instead of multiple, in order to reduce potential
incompatiblities.

renovate.json

@@ -49,6 +49,14 @@
         "registry.fedoraproject.org/fedora"
       ],
       "allowedVersions": "<38"
+    },
+    {
+      "matchDatasources": ["flux"],
+      "packageNames": [
+        "rook-ceph",
+        "rook-ceph-cluster"
+      ],
+      "groupName": "rook-ceph"
     }
   ]
 }