Wait for process termination during isolation tests

slot_creation_error.spec and temp-schema-cleanup.spec used
pg_terminate_backend() without specifying timeout, thus there may be a
case of proceeding to the next step before the process actually
terminates then false failure.

Supply timeout to pg_terminate_backend() so that it waits for process
termination to avoid that failure mode.

Author: horiguti

contrib/test_decoding/expected/slot_creation_error.out

@@ -88,7 +88,7 @@ step s2_init:
     SELECT 'init' FROM pg_create_logical_replication_slot('slot_creation_error', 'test_decoding');
  <waiting ...>
 step s1_terminate_s2: 
-    SELECT pg_terminate_backend(pid)
+    SELECT pg_terminate_backend(pid, 180000)
     FROM pg_stat_activity
     WHERE application_name = 'isolation/slot_creation_error/s2';
  <waiting ...>

contrib/test_decoding/specs/slot_creation_error.spec

@@ -13,7 +13,7 @@ step s1_cancel_s2 {
 }
 
 step s1_terminate_s2 {
-    SELECT pg_terminate_backend(pid)
+    SELECT pg_terminate_backend(pid, 180000)
     FROM pg_stat_activity
     WHERE application_name = 'isolation/slot_creation_error/s2';
 }

src/test/isolation/expected/temp-schema-cleanup.out

@@ -87,7 +87,7 @@ exec
 s1: NOTICE:  function "uses_a_temp_type" will be effectively temporary
 DETAIL:  It depends on temporary type just_give_me_a_type.
 step s1_exit: 
-    SELECT pg_terminate_backend(pg_backend_pid());
+    SELECT pg_terminate_backend(pg_backend_pid(), 180000);
 
 FATAL:  terminating connection due to administrator command
 server closed the connection unexpectedly

src/test/isolation/specs/temp-schema-cleanup.spec

@@ -47,7 +47,7 @@ step s1_discard_temp {
 }
 
 step s1_exit {
-    SELECT pg_terminate_backend(pg_backend_pid());
+    SELECT pg_terminate_backend(pg_backend_pid(), 180000);
 }