pgsql: postgres_fdw: Fix thinko in comment for UserMappingPasswordRequi

postgres_fdw: Fix thinko in comment for UserMappingPasswordRequired().

This commit also rephrases this comment to improve readability.

Oversight in commit 6136e94dc.

Reported-by: Etsuro Fujita <etsuro.fujita@gmail.com>
Author: Andreas Karlsson <andreas@proxel.se>
Co-authored-by: Etsuro Fujita <etsuro.fujita@gmail.com>
Discussion: /messages/by-id/CAPmGK16pDnM_wU3kmquPj-M9MYqG3y0BdntRZ0eytqbCaFY3WQ@mail.gmail.com
Backpatch-through: 14

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/e7b97a22383a5310e0cf643468f648666de3970f

Modified Files
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contrib/postgres_fdw/connection.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)