pgsql: Fix inconsistencies in error messages

Fix inconsistencies in error messages

Reported by Kyotaro Horiguchi

Also some comments mentioning wrong version numbers, spotted by Justin
Pryzby.

Discussion: https://postgr.es/m/20240507.171724.750916195320223609.horikyota.ntt@gmail.com
Discussion: https://postgr.es/m/Zh0aAH7tbZb-9HbC@pryzbyj2023

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/21ac38f498b33f0231842238b83847ec63dfe07b

Modified Files
--------------
src/backend/catalog/pg_constraint.c   | 2 +-
src/backend/commands/tablecmds.c      | 3 +--
src/bin/pg_dump/common.c              | 2 +-
src/bin/pg_dump/pg_dump.c             | 2 +-
src/test/regress/expected/inherit.out | 4 ++--
5 files changed, 6 insertions(+), 7 deletions(-)