Test corner_cases fails due to timing issues.

[ziva777]

On "slow" runs we can get something like this:

test corner_cases                 ... FAILED     8738 ms

======================
 1 of 1 tests failed. 
======================

The differences that caused some tests to fail can be viewed in the
file "/bf/ENT_master/pgsql.build/contrib/pg_query_state/isolation_output/regression.diffs".  A copy of the test summary that you see
above is saved in the file "/bf/ENT_master/pgsql.build/contrib/pg_query_state/isolation_output/regression.out".

make[1]: *** [Makefile:35: installcheck] Ошибка 1
make[1]: выход из каталога «/bf/ENT_master/pgsql.build/contrib/pg_query_state»
make: *** [Makefile:116: installcheck-pg_query_state-recurse] Ошибка 2


================= pgsql.build/contrib/pg_query_state/isolation_output/regression.diffs ===================
diff -U3 /bf/ENT_master/pgsql.build/contrib/pg_query_state/expected/corner_cases.out /bf/ENT_master/pgsql.build/contrib/pg_query_state/isolation_output/results/corner_cases.out
--- /bf/ENT_master/pgsql.build/contrib/pg_query_state/expected/corner_cases.out	2021-11-05 04:05:56.529952097 +0300
+++ /bf/ENT_master/pgsql.build/contrib/pg_query_state/isolation_output/results/corner_cases.out	2021-11-05 06:53:58.446478561 +0300
@@ -66,7 +66,8 @@
 (1 row)
 
 s2: INFO:  state of backend is idle
-step s2_pg_qs_counterpart: select pg_query_state(counterpart_pid(0));
+step s2_pg_qs_counterpart: select pg_query_state(counterpart_pid(0)); <waiting ...>
+step s2_pg_qs_counterpart: <... completed>
 pg_query_state
 --------------
 (0 rows)```