Improve cleanup phases in regression tests of pg_stat_statements
As shaped, two DROP ROLE queries included in "user_activity" were
showing in the reports for "wal". The intention is to keep each test
isolated and independent, so this is incorrect. This commit adds some
calls to pg_stat_statements_reset() to clean up the statistics once each
test finishes, so as there are no risks of overlap in the reports for
individial scenarios.
The addition in "user_activity" fixes the output of "wal". The new
resets done in "level_tracking" and "utility" are added for consistency
with the rest, though they do not affect the stats generated in the
other tests.
Oversight in
d0028e3.
Reported-by: Andrei Zubkov
Discussion: https://postgr.es/m/
7beb722dd016bf54f1c78bfd6d44a684e28da624.camel@moonset.ru