pgsql: doc: Remove incorrect libpq environment reference from pg_combin

doc: Remove incorrect libpq environment reference from pg_combinebackup

The Environment section of pg_combinebackup.sgml incorrectly stated
that pg_combinebackup uses libpq environment variables, suggesting
that connection settings such as PGHOST and PGPORT affect its behavior.
However, pg_combinebackup operates on local backup directories and
does not use libpq or connect to a server.

Remove the incorrect paragraph.

Backpatch to 17, where pg_combinebackup was introduced.

Author: Sai Pranav <rajasaipranav0(at)gmail(dot)com>
Reviewed-by: Fujii Masao <masao(dot)fujii(at)gmail(dot)com>
Discussion: https://postgr.es/m/CAPHduZAYBNVWkXAsrXXrb+dD2gKDABcJfcudXQecFdW2WEpDdw@mail.gmail.com
Backpatch-through: 17

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/be2d360e843f38c8e057cc6e160cb00d7badc297

Modified Files
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doc/src/sgml/ref/pg_combinebackup.sgml | 6 ------
1 file changed, 6 deletions(-)