GetNextNodeId() incorrectly called PG_RETURN_DATUM

- Also stabilize the output of a multi_router_planner test

src/backend/distributed/utils/node_metadata.c

@@ -1192,20 +1192,18 @@ GetNextNodeId()
 	Datum sequenceIdDatum = ObjectIdGetDatum(sequenceId);
 	Oid savedUserId = InvalidOid;
 	int savedSecurityContext = 0;
-	Datum nextNodedIdDatum = 0;
+	Datum nextNodeIdDatum;
 	int nextNodeId = 0;
 
 	GetUserIdAndSecContext(&savedUserId, &savedSecurityContext);
 	SetUserIdAndSecContext(CitusExtensionOwner(), SECURITY_LOCAL_USERID_CHANGE);
 
 	/* generate new and unique shardId from sequence */
-	nextNodedIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
+	nextNodeIdDatum = DirectFunctionCall1(nextval_oid, sequenceIdDatum);
 
 	SetUserIdAndSecContext(savedUserId, savedSecurityContext);
 
-	PG_RETURN_DATUM(nextNodedIdDatum);
+	nextNodeId = DatumGetUInt32(nextNodeIdDatum);
-
-	nextNodeId = DatumGetUInt32(nextNodeId);
 
 	return nextNodeId;
 }

src/test/regress/expected/multi_mx_router_planner.out

@@ -1153,7 +1153,8 @@ SELECT
 	FROM
 		articles_hash_mx
  	GROUP BY
-		author_id;
+		author_id
+	ORDER BY c;
  c 
 ---
  4

src/test/regress/expected/multi_router_planner.out

@@ -1832,7 +1832,8 @@ SELECT
 	FROM
 		articles_hash
  	GROUP BY
-		author_id;
+		author_id
+	ORDER BY c;
  c 
 ---
  4

src/test/regress/sql/multi_mx_router_planner.sql

@@ -530,7 +530,8 @@ SELECT
 	FROM
 		articles_hash_mx
  	GROUP BY
-		author_id;
+		author_id
+	ORDER BY c;
 
 -- queries inside transactions can be router plannable
 BEGIN;

src/test/regress/sql/multi_router_planner.sql

@@ -900,7 +900,8 @@ SELECT
 	FROM
 		articles_hash
  	GROUP BY
-		author_id;
+		author_id
+	ORDER BY c;
 
 -- queries inside transactions can be router plannable
 BEGIN;