pgsql: Adapt appendPsqlMetaConnect() to the new fmtId() encoding expect

Adapt appendPsqlMetaConnect() to the new fmtId() encoding expectations.

We need to tell fmtId() what encoding to assume, but this function
doesn't know that. Fortunately we can fix that without changing the
function's API, because we can just use SQL_ASCII. That's because
database names in connection requests are effectively binary not text:
no encoding-aware processing will happen on them.

This fixes XversionUpgrade failures seen in the buildfarm. The
alternative of having pg_upgrade use setFmtEncoding() is unappetizing,
given that it's connecting to multiple databases that may have
different encodings.

Andres Freund, Noah Misch, Tom Lane

Security: CVE-2025-1094

Branch
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REL_16_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/0075a5c6ce5bb6f3ee005a54cd5b518f16659655

Modified Files
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src/fe_utils/string_utils.c | 19 ++++++++++++++-----
1 file changed, 14 insertions(+), 5 deletions(-)