[PATCH] Fix TOCTOU races in recovery/t/020_archive_status.pl archive checks

Greetings,

recovery/t/020_archive_status.pl checks archiving progress in two separate
queries: it polls pg_stat_archiver for one condition, then asserts a related
one.  For the primary it polls until archived_count is exactly 1, then
separately asserts last_archived_wal equals a specific segment; for the
always-on standby it polls until last_archived_wal equals a segment, then
asserts archived_count is exactly 2.

Both are racy.  A checkpoint or crash-recovery segment archived between the
two queries pushes the count or last_archived_wal past the exact value
expected.  The exact-equality poll is fragile on its own, too: if the count
jumps past the target, the poll never sees it and times out.

The fix uses monotonic >= instead of exact equality, so the checks tolerate
extra archived segments.  WAL segment names sort lexically, so >= is
well defined for last_archived_wal.

--
Bryan Green
EDB: https://www.enterprisedb.com