[chore] group github.com/twmb/franz-go updates in renovate (#47994)

#### Description
Group dependency updates of github.com/twmb/franz-go packages together,
e.g. see
#47992
&
#47991

Author: songy23

renovate.json

@@ -240,6 +240,15 @@
         "github.com/splunk/stef{/,}**"
       ]
     },
+    {
+      "matchManagers": [
+        "gomod"
+      ],
+      "groupName": "All github.com/twmb/franz-go packages",
+      "matchPackageNames": [
+        "github.com/twmb/franz-go{/,}**"
+      ]
+    },
     {
       "matchPackageNames": [
         "github.com/vmware/govmomi"