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_12_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/8358eacc954d85bdb8140f013b41c6650d22e5ca

Modified Files
--------------
src/bin/pg_checksums/t/002_actions.pl            |  1 -
src/test/perl/PostgresNode.pm                    |  4 ++--
src/test/perl/TestLib.pm                         | 27 ------------------------
src/test/recovery/t/014_unlogged_reinit.pl       |  4 +---
src/test/recovery/t/017_shm.pl                   |  2 +-
src/test/recovery/t/025_stuck_on_old_timeline.pl |  2 +-
6 files changed, 5 insertions(+), 35 deletions(-)