Fix Subscription test added by commit ce0fdbfe.

We want to test the variants of Alter Subscription that are not allowed in
the transaction block but for that, we don't need to create a subscription
that tries to connect to the publisher. As such, there is no problem with
this test but it is good to allow such tests to run with
wal_level = minimal and max_wal_senders = 0 so as to keep them consistent
with other tests.

Reported by buildfarm.

Author: Amit Kapila
Reviewed-by: Ajin Cherian
Discussion: https://postgr.es/m/CAA4eK1Lw0V+e1JPGHDq=+hVACv=14H8sR+2eJ1k3PEgwKmU-jQ@mail.gmail.com

src/test/regress/expected/subscription.out

@@ -201,8 +201,10 @@ ALTER SUBSCRIPTION regress_testsub SET (slot_name = NONE);
 (1 row)
 
 DROP SUBSCRIPTION regress_testsub;
-CREATE SUBSCRIPTION regress_testsub CONNECTION 'dbname=postgres' PUBLICATION mypub
-       WITH (enabled = true, create_slot = false, copy_data = false);
+CREATE SUBSCRIPTION regress_testsub CONNECTION 'dbname=regress_doesnotexist' PUBLICATION mypub
+       WITH (connect = false, create_slot = false, copy_data = false);
+WARNING:  tables were not subscribed, you will have to run ALTER SUBSCRIPTION ... REFRESH PUBLICATION to subscribe the tables
+ALTER SUBSCRIPTION regress_testsub ENABLE;
 -- fail - ALTER SUBSCRIPTION with refresh is not allowed in a transaction
 -- block or function
 BEGIN;

src/test/regress/sql/subscription.sql

@@ -147,8 +147,10 @@ ALTER SUBSCRIPTION regress_testsub SET (slot_name = NONE);
 
 DROP SUBSCRIPTION regress_testsub;
 
-CREATE SUBSCRIPTION regress_testsub CONNECTION 'dbname=postgres' PUBLICATION mypub
-       WITH (enabled = true, create_slot = false, copy_data = false);
+CREATE SUBSCRIPTION regress_testsub CONNECTION 'dbname=regress_doesnotexist' PUBLICATION mypub
+       WITH (connect = false, create_slot = false, copy_data = false);
+
+ALTER SUBSCRIPTION regress_testsub ENABLE;
 
 -- fail - ALTER SUBSCRIPTION with refresh is not allowed in a transaction
 -- block or function