Fix multi_follower_dml

When the_table is emtpy, we don't get an error with pg14 anymore so we
replace it generate_series so that we get the error.

src/test/regress/expected/multi_follower_dml.out

@@ -243,7 +243,7 @@ SELECT * FROM citus_local_table ORDER BY a;
 -- we should still disallow writes to local tables
 INSERT INTO local VALUES (1, 1);
 ERROR:  cannot execute INSERT in a read-only transaction
-INSERT INTO local SELECT a, b FROM the_table;
+INSERT INTO local SELECT i,i FROM generate_series(0,100)i;
 ERROR:  cannot execute INSERT in a read-only transaction
 -- we shouldn't be able to create local tables
 CREATE TEMP TABLE local_copy_of_the_table AS SELECT * FROM the_table;

src/test/regress/sql/multi_follower_dml.sql

@@ -135,7 +135,7 @@ SELECT * FROM citus_local_table ORDER BY a;
 
 -- we should still disallow writes to local tables
 INSERT INTO local VALUES (1, 1);
-INSERT INTO local SELECT a, b FROM the_table;
+INSERT INTO local SELECT i,i FROM generate_series(0,100)i;
 
 -- we shouldn't be able to create local tables
 CREATE TEMP TABLE local_copy_of_the_table AS SELECT * FROM the_table;