pgsql: Fix a few duplicate words in comments

Fix a few duplicate words in comments

These are all new to v18

Author: David Rowley <dgrowleyml@gmail.com>
Discussion: https://postgr.es/m/CAApHDvrMcr8XD107H3NV=WHgyBcu=sx5+7=WArr-n_cWUqdFXQ@mail.gmail.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/84fd3bc141039b32f25c3c9f6157163a56ab5f66

Modified Files
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contrib/amcheck/verify_heapam.c               | 2 +-
contrib/pg_buffercache/pg_buffercache_pages.c | 4 ++--
src/backend/access/nbtree/nbtpreprocesskeys.c | 2 +-
src/backend/access/nbtree/nbtutils.c          | 2 +-
src/backend/executor/execPartition.c          | 4 ++--
src/backend/utils/adt/pg_locale.c             | 2 +-
src/backend/utils/mmgr/mcxt.c                 | 6 +++---
src/bin/pg_upgrade/relfilenumber.c            | 4 ++--
src/include/storage/aio.h                     | 2 +-
9 files changed, 14 insertions(+), 14 deletions(-)