pgsql: Remove PostgreSQL::Test::Utils::perl2host completely

Remove PostgreSQL::Test::Utils::perl2host completely

Commit f1ac4a74de disabled this processing, and as nothing has broken (as
expected) here we proceed to remove the routine and adjust all the call
sites.

Backpatch to release 10

Discussion: https://postgr.es/m/0ba775a2-8aa0-0d56-d780-69427cf6f33d@dunslane.net
Discussion: https://postgr.es/m/20220125023609.5ohu3nslxgoygihl@alap3.anarazel.de

Branch
------
REL_10_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/b30c62bd42ebdee366919b9cfcf62a489031b571

Modified Files
--------------
src/test/perl/PostgresNode.pm                    |  4 ++--
src/test/perl/TestLib.pm                         | 27 ------------------------
src/test/recovery/t/025_stuck_on_old_timeline.pl |  2 +-
3 files changed, 3 insertions(+), 30 deletions(-)