pgsql: Fix intermittent BF failure in 040_standby_failover_slots_sync.

Fix intermittent BF failure in 040_standby_failover_slots_sync.

Commit 0d2d4a0ec3 introduced a test that verifies replication slot
synchronization to a standby server via SQL API. However, the test did not
configure synchronized_standby_slots. Without this setting, logical
failover slots can advance beyond the physical replication slot, causing
intermittent synchronization failures.

Author: Hou Zhijie <houzj.fnst@fujitsu.com>
Discussion: https://postgr.es/m/TY4PR01MB16907DF70205308BE918E0D4494ABA@TY4PR01MB16907.jpnprd01.prod.outlook.com

Branch
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master

Details
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https://git.postgresql.org/pg/commitdiff/b47c50e5667b489bec3affb55ecdf4e9c306ca2d

Modified Files
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src/test/recovery/t/040_standby_failover_slots_sync.pl | 8 ++++++++
1 file changed, 8 insertions(+)