pgsql: pg_combinebackup: Fix incorrect code documentation

pg_combinebackup: Fix incorrect code documentation

The code comment for parse_oid accidentally used the wrong parameter
when referring to the location of the last backup. Also, while there,
improve sentence wording by removing a superfluous word.

Backpatch to v17 where pg_combinebackup was addedd

Author: Amul Sul <sulamul@gmail.com>
Reviewed-by: Daniel Gustafsson <daniel@yesql.se>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: /messages/by-id/CAAJ_b95ecWgzcS4K3Dx0E_Yp-SLwK5JBasFgioKMSjhQLw9xvg@mail.gmail.com
Backpatch-through: 17

Branch
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REL_17_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/fb9ec9cf79263329ca8f116d6dacaada78f49dc2

Modified Files
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src/bin/pg_combinebackup/pg_combinebackup.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)