Disable test for postgres -C on Msys

Disable test for postgres -C on Msys

The output generated on Msys is incorrect because of the different way
IPC::Run processes outputs with native Perl (converts natively \r\n to
\n) and Msys perl (\r\n kept as-is), causing this test to fail.

For now, just disable the test to bring the buildfarm to a green state.
I think that the correct long-term solution would be to tweak all the
routines command_checks_* in PostgresNode.pm to handle this output like
psql does when using Msys, by discarding \r automatically before
comparing it.

Per report from jacana and fairywren.  Thanks to Tom Lane for the ping.

Discussion: https://postgr.es/m/1252480.1631829409@sss.pgh.pa.us