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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master

Details
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https://git.postgresql.org/pg/commitdiff/03bf0d9a4ba0fb7a908b5a79eb80e0c983b51e87

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(-)