pgsql: Revert "Mark modified the FSM buffer as dirty during recovery"

Revert "Mark modified the FSM buffer as dirty during recovery"

This reverts commit c06d1a4ba6b26eef27b04074683cccade6c277ee.

The commit assumed that if the FSM code tolerates torn pages, everything else
does so. Readers that do not tolerate that include RelationCopyStorage(),
used by ALTER TABLE ... SET TABLESPACE for every fork, the read stream in
RelationCopyStorageUsingBuffer() used by CREATE DATABASE ... STRATEGY =
wal_log, and, most awkwardly, the checksum verification in base backups and
pg_checksums.

Reported-by: Noah Misch <noah(at)leadboat(dot)com>
Discussion: https://postgr.es/m/20260901211837.f6.noahmisch%40microsoft.com
Backpatch-through: 14
Reviewed-by: Andrey Borodin <x4mmm(at)yandex-team(dot)ru>

Branch
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REL_18_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/5d63dbd9774dcb28d7c88bfce42505376b201861

Modified Files
--------------
src/backend/storage/freespace/freespace.c | 12 +-----------
1 file changed, 1 insertion(+), 11 deletions(-)