EnsureCoordinator() for GRANT on TABLE propagation

In the table/table(attribute) cases, we didn't checked if the command
was run from the Coordinator.

Add the check where suggested by @naisila in https://github.com/citusdata/citus/pull/7918#pullrequestreview-2702649595

src/backend/distributed/commands/grant.c

@@ -70,6 +70,8 @@ PreprocessGrantStmt(Node *node, const char *queryString,
 		return NIL;
 	}
 
+	EnsureCoordinator();
+
 	/* deparse the privileges */
 	if (grantStmt->privileges == NIL)
 	{