pgsql: Put back explicit setting of replication values within TAP tests

Put back explicit setting of replication values within TAP tests.

Commit 151c0c5f7 neglected the possibility that a TEMP_CONFIG file
would explicitly set max_wal_senders=0; as indeed buildfarm member
thorntail does, so that it can test wal_level=minimal in other test
suites. Hence, rather than assuming that max_wal_senders=10 will
prevail if we say nothing, set it explicitly.

Set max_replication_slots=10 explicitly too, just to be safe.

Back-patch to v10, like the previous patch.

Discussion: https://postgr.es/m/723911.1601417626@sss.pgh.pa.us

Branch
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REL_13_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/6731f1ef19fdf912cfbf2686a4d344a022b7704b

Modified Files
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src/test/perl/PostgresNode.pm | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)