pgsql: Clean up error message reported after \password encryption failu

Clean up error message reported after \password encryption failure.

Experimenting with FIPS mode enabled, I saw

regression=# \password joe
Enter new password for user "joe":
Enter it again:
could not encrypt password: disabled for FIPS
out of memory

because PQencryptPasswordConn was still of the opinion that "out of
memory" is always appropriate to print.

Minor oversight in b69aba745. Like that one, back-patch to v14.

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/9cb5518b7ff69ab3bbc422313c69d54696fe8472

Modified Files
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src/interfaces/libpq/fe-auth.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)