Fix two portability issues with the tests of test_oat_hooks

This addresses two issues in the tests of test_oat_hooks:
- The role regress_test_user was being left behind, preventing the test
to succeed on repeated runs.  It makes sense to leave some objects
behind to have more coverage for pg_upgrade (as does test_pg_dump), but
the role dropped here does not own any objects so there is no reason to
keep it.
- GRANT SET ON PARAMETER is issued, creating an entry in
pg_parameter_acl without cleaning up the entry created.  This causes
an overlap with unsafe_tests as both use work_mem, making the latter
fail.  This commit adds an extra REVOKE SET ON PARAMETER to clean the
contents of pg_parameter_acl, switching to maintenance_work_mem rather
than work_mem to avoid an overlap between both tests.

The tests of test_oat_hooks cannot use installcheck yet as these are
proving to be unstable with caching and the namespace search hooks, so
the issues fixed here cannot be reached yet, but they would be once the
hook issue is addressed and installcheck is allowed again in
test_oat_hooks.

Discussion: https://postgr.es/m/YrpVkADAY0knF6vM@paquier.xyz
Backpatch-through: 15

Author: michaelpq

src/test/modules/test_oat_hooks/expected/test_oat_hooks.out

@@ -41,10 +41,13 @@ privileges for parameter test_oat_hooks.super_var2
 privileges for parameter none.such
 privileges for parameter another.bogus
 -- Check the behavior of the hooks relative to do-nothing grants and revokes
-GRANT SET ON PARAMETER work_mem TO PUBLIC;
+GRANT SET ON PARAMETER maintenance_work_mem TO PUBLIC;
 NOTICE:  in process utility: superuser attempting GrantStmt
 NOTICE:  in process utility: superuser finished GrantStmt
-REVOKE ALTER SYSTEM ON PARAMETER work_mem FROM PUBLIC;
+REVOKE SET ON PARAMETER maintenance_work_mem FROM PUBLIC;
+NOTICE:  in process utility: superuser attempting GrantStmt
+NOTICE:  in process utility: superuser finished GrantStmt
+REVOKE ALTER SYSTEM ON PARAMETER maintenance_work_mem FROM PUBLIC;
 NOTICE:  in process utility: superuser attempting GrantStmt
 NOTICE:  in process utility: superuser finished GrantStmt
 -- Check the behavior of the hooks relative to unrecognized parameters
@@ -299,3 +302,4 @@ REVOKE ALL PRIVILEGES ON PARAMETER
 	test_oat_hooks.user_var2, test_oat_hooks.super_var2
 	FROM regress_role_joe;
 DROP ROLE regress_role_joe;
+DROP ROLE regress_test_user;

src/test/modules/test_oat_hooks/sql/test_oat_hooks.sql

@@ -25,8 +25,9 @@ GRANT SET, ALTER SYSTEM ON PARAMETER another.bogus TO regress_role_joe WITH GRAN
 DROP ROLE regress_role_joe;
 
 -- Check the behavior of the hooks relative to do-nothing grants and revokes
-GRANT SET ON PARAMETER work_mem TO PUBLIC;
-REVOKE ALTER SYSTEM ON PARAMETER work_mem FROM PUBLIC;
+GRANT SET ON PARAMETER maintenance_work_mem TO PUBLIC;
+REVOKE SET ON PARAMETER maintenance_work_mem FROM PUBLIC;
+REVOKE ALTER SYSTEM ON PARAMETER maintenance_work_mem FROM PUBLIC;
 
 -- Check the behavior of the hooks relative to unrecognized parameters
 GRANT ALL ON PARAMETER "none.such" TO PUBLIC;
@@ -98,3 +99,4 @@ REVOKE ALL PRIVILEGES ON PARAMETER
 	test_oat_hooks.user_var2, test_oat_hooks.super_var2
 	FROM regress_role_joe;
 DROP ROLE regress_role_joe;
+DROP ROLE regress_test_user;