pgsql: Remove some unstable parts from new TAP test for archive status

Remove some unstable parts from new TAP test for archive status check

The test is proving to have timing issues when looking at archive status
files on standbys after crash recovery, while other parts of the test
rely on pg_stat_archiver as a wait point to make sure that a given state
of the archiving is reached. The coverage is not heavily impacted by
the removal those extra tests.

Per reports from several buildfarm animals, like crake, piculet,
culicidae and francolin.

Discussion: https://postgr.es/m/20200424005929.GK33034@paquier.xyz
Backpatch-through: 9.5

Branch
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REL9_6_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/11f0046996e1222e7eb2ee2c9597a37481773ae8

Modified Files
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src/test/recovery/t/020_archive_status.pl | 18 +-----------------
1 file changed, 1 insertion(+), 17 deletions(-)