pgsql: Rewrite some regression queries for option checks with COPY

Rewrite some regression queries for option checks with COPY

Some queries in copy2 are there to check various option combinations,
and used "stdin" or "stdout" incompatible with the COPY TO or FROM
clauses combined with them, which was confusing. This commit rewrites
these queries to use a compatible grammar.

The coverage of the tests is unchanged. Like the original commit
451d1164b9d0, backpatch down to 16 where these have been introduced. A
follow-up commit will rely on this area of the tests for a bug fix.

Author: Joel Jacobson
Reviewed-by: Zhang Mingli
Discussion: https://postgr.es/m/65030d1d-5f90-4fa4-92eb-f5f50389858e@app.fastmail.com
Backpatch-through: 16

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/a30c1ca21c584cb0917a5e6fbe086164cd8bec6a

Modified Files
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src/test/regress/expected/copy2.out | 26 +++++++++++++-------------
src/test/regress/sql/copy2.sql | 18 +++++++++---------
2 files changed, 22 insertions(+), 22 deletions(-)