pgsql: Finish reverting "Insert temporary debugging output in regressio

Finish reverting "Insert temporary debugging output in regression tests."

This removes the last of the temporary debugging queries added to the
regression tests by commit f03a9ca43.  We've pretty much convinced
ourselves that the plan instability we were seeing is due to VACUUM
sometimes failing to update relpages/reltuples for a single-page table,
due to bgwriter or checkpointer holding a pin on that page at just the
wrong time.  I'll push a workaround for that separately.

Discussion: https://postgr.es/m/CA+hUKG+0CxrKRWRMf5ymN3gm+BECHna2B-q1w8onKBep4HasUw@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/d9cacca2d139d9e0792544f773d2361d8478c131

Modified Files
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src/test/regress/expected/select_parallel.out | 14 --------------
src/test/regress/sql/select_parallel.sql      |  5 -----
2 files changed, 19 deletions(-)