No superuser check separated from other tests

The output differs across versions because it can include the context.

This made:

- repack.out = repack_1.out
- repack_3.out = repack_5.out

regress/sql/nosuper.sql

@@ -0,0 +1,14 @@
+--
+-- no superuser check
+--
+SET client_min_messages = error;
+DROP ROLE IF EXISTS nosuper;
+SET client_min_messages = warning;
+CREATE ROLE nosuper WITH LOGIN;
+-- => OK
+\! pg_repack --dbname=contrib_regression --table=tbl_cluster --no-superuser-check
+-- => ERROR
+\! pg_repack --dbname=contrib_regression --table=tbl_cluster --username=nosuper
+-- => ERROR
+\! pg_repack --dbname=contrib_regression --table=tbl_cluster --username=nosuper --no-superuser-check
+DROP ROLE IF EXISTS nosuper;

regress/sql/repack.sql

@@ -291,19 +291,6 @@ CREATE TABLE test_schema2.tbl2 (id INTEGER PRIMARY KEY);
 --
 \! pg_repack --dbname=contrib_regression --table=tbl_cluster --no-kill-backend
 
---
--- no superuser check
---
-DROP ROLE IF EXISTS nosuper;
-CREATE ROLE nosuper WITH LOGIN;
--- => OK
-\! pg_repack --dbname=contrib_regression --table=tbl_cluster --no-superuser-check
--- => ERROR
-\! pg_repack --dbname=contrib_regression --table=tbl_cluster --username=nosuper
--- => ERROR
-\! pg_repack --dbname=contrib_regression --table=tbl_cluster --username=nosuper --no-superuser-check
-DROP ROLE IF EXISTS nosuper;
-
 --
 -- exclude extension check
 --