Remove unstable test for pg_statio_all_sequences stats reset

Remove unstable test for pg_statio_all_sequences stats reset

Commit 8fe315f18d4 added the stats_reset column to pg_statio_all_sequences and
included a regression test to verify that statistics in this view are reset
correctly. However, this test caused buildfarm member crake to report
a pg_upgradeCheck failure.

The failing test assumed that the blks_read and blks_hit counters
in pg_statio_all_sequences would be zero after calling
pg_stat_reset_single_table_counters(). On crake, however, either blks_read or
blks_hit sometimes appeared as 1 during the pg_upgradeCheck test, even right
after the reset.

Since these counters may change due to concurrent activity and the test is
unstable, this commit removes the checks for blks_read and blks_hit in
pg_statio_all_sequences from the regression test.

Per buildfarm member crake.

Discussion: https://postgr.es/m/CAHGQGwFcay_tX=7HSS=N=+Yd0FLEm2GrJgwxnqHM4wvxX0B=4g@mail.gmail.com