pgsql: Remove most msys special processing in TAP tests

Remove most msys special processing in TAP tests

Following migration of Windows buildfarm members running TAP tests to
use of ucrt64 perl for those tests, special processing for msys perl is
no longer necessary and so is removed.

Backpatch to release 10

Discussion: https://postgr.es/m/c65a8781-77ac-ea95-d185-6db291e1baeb@dunslane.net

Branch
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REL_11_STABLE

Details
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https://git.postgresql.org/pg/commitdiff/f1f82301d6c5db8afef3729da0582b2dafca1103

Modified Files
--------------
src/bin/pg_ctl/t/001_start_stop.pl   | 11 +----------
src/bin/pg_rewind/t/RewindTest.pm    |  1 -
src/test/perl/PostgresNode.pm        | 15 +--------------
src/test/perl/TestLib.pm             |  5 -----
src/test/recovery/t/cp_history_files |  7 -------
5 files changed, 2 insertions(+), 37 deletions(-)