PG-295: Fix top_query regression test.

The issue is that between changing GUC "track" from track='top' to
track='all' the queries are executing using previous state of
track='top', to fix that we sleep 1 second after calling
pg_reload_conf() to ensure that queries will run with new settings.

regression/expected/top_query.out

@@ -48,6 +48,12 @@ SELECT pg_reload_conf();
  t
 (1 row)
 
+SELECT pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
 SELECT pg_stat_monitor_reset();
  pg_stat_monitor_reset 
 -----------------------
@@ -98,6 +104,12 @@ SELECT pg_reload_conf();
  t
 (1 row)
 
+SELECT pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
 SELECT pg_stat_monitor_reset();
  pg_stat_monitor_reset 
 -----------------------

regression/expected/top_query_1.out

@@ -48,6 +48,12 @@ SELECT pg_reload_conf();
  t
 (1 row)
 
+SELECT pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
 SELECT pg_stat_monitor_reset();
  pg_stat_monitor_reset 
 -----------------------
@@ -98,6 +104,12 @@ SELECT pg_reload_conf();
  t
 (1 row)
 
+SELECT pg_sleep(1);
+ pg_sleep 
+----------
+ 
+(1 row)
+
 SELECT pg_stat_monitor_reset();
  pg_stat_monitor_reset 
 -----------------------

regression/sql/top_query.sql

@@ -19,6 +19,7 @@ SELECT query, top_query FROM pg_stat_monitor ORDER BY query COLLATE "C";
 
 ALTER SYSTEM SET pg_stat_monitor.track TO 'all';
 SELECT pg_reload_conf();
+SELECT pg_sleep(1);
 SELECT pg_stat_monitor_reset();
 
 CREATE OR REPLACE FUNCTION add(int, int) RETURNS INTEGER AS
@@ -38,6 +39,7 @@ SELECT add2(1,2);
 SELECT query, top_query FROM pg_stat_monitor ORDER BY query COLLATE "C";
 ALTER SYSTEM SET pg_stat_monitor.track TO 'top';
 SELECT pg_reload_conf();
+SELECT pg_sleep(1);
 SELECT pg_stat_monitor_reset();
 
 DROP EXTENSION pg_stat_monitor;