Ensure standby promotion point in 043_wal_replay_wait.pl
This commit ensures standby will be promoted at least at the primary insert
LSN we have just observed. We use pg_switch_wal() to force the insert LSN
to be written then wait for standby to catchup.
Reported-by: Alexander Lakhin
Discussion: https://postgr.es/m/
1d7b08f2-64a2-77fb-c666-
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