pgsql: Fix spelling and punctuation

Fix spelling and punctuation

Remove trailing periods from pg_log_error emitted strings as only
hint and detail level error messages should be punctuated.  Also
reword the usage screen which was missing a word.

Author: Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Discussion: https://postgr.es/m/20231130.105223.554982964895179414.horikyota.ntt@gmail.com
Discussion: https://postgr.es/m/20231130.103900.2069212175914114279.horikyota.ntt@gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b3efa270b5192f0c72dc26f0ea1bc795ad8516c3

Modified Files
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src/bin/pg_dump/pg_dump.c    | 6 +++---
src/bin/pg_dump/pg_dumpall.c | 4 ++--
src/bin/pg_dump/pg_restore.c | 4 ++--
3 files changed, 7 insertions(+), 7 deletions(-)