grafana: fix probe status table join

Use joinByField transformation instead of merge to properly align
rows by instance. Also exclude duplicate Time/job columns from join.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

services/grafana/dashboards/certificates.json

@@ -279,12 +279,16 @@
       ],
       "transformations": [
         {
-          "id": "merge"
+          "id": "joinByField",
+          "options": {
+            "byField": "instance",
+            "mode": "outer"
+          }
         },
         {
           "id": "organize",
           "options": {
-            "excludeByName": {"Time": true, "job": true, "__name__": true},
+            "excludeByName": {"Time": true, "Time 1": true, "Time 2": true, "Time 3": true, "job": true, "job 1": true, "job 2": true, "job 3": true, "__name__": true},
             "renameByName": {
               "instance": "Endpoint",
               "Value #A": "Success",