egress board: the host tables merge their frames, so they are tables and not a series dropdown

A grouped stats query is one frame per group. Labels become columns,
then the frames merge into rows.

nix/module-eval/grafana.nix

@@ -496,6 +496,16 @@ let
         && lib.all (e: lib.hasInfix "\"TCP_\"*" e) (
           lib.filter (e: lib.hasInfix access e) (exprs ++ [ agentVar.spec.query.spec.query ])
         )
+        # A grouped stats query is one frame per group, which a table panel shows as
+        # a dropdown of series; labels to columns, then a merge, makes the rows.
+        && lib.all (
+          e:
+          map (t: t.spec.id) e.spec.data.spec.transformations == [
+            "labelsToFields"
+            "merge"
+            "organize"
+          ]
+        ) (lib.filter (e: e.spec.vizConfig.group == "table") (lib.attrValues board.spec.elements))
         && lib.hasInfix "logformat would_deny would_deny user=%[un method=%rm host=%>rd port=%>rP result=" squid
         && lib.hasInfix "access_log syslog:daemon.info squid !manager" squid;
     }