TT#50954 Disable perlcritic's InputOutput::ProhibitExplicitStdin policy

This policy is giving bad advice. The <> operator is security unsafe, as
it interprets filenames as if passed to the two-form open function,
which means it can do code injection via crafted filenames.

While reading from <STDIN> directly might not always be correct, its
consequences are far milder than the damage inflicted by the diamond
operator.

Change-Id: I0fdf097be3b5e2a3a483f2e5d80f4fdb1f17911b

t/tap-tests-docker/perlcriticrc

@@ -68,6 +68,9 @@ severity = 4
 # XXX: Perhaps. Enable per project.
 [-InputOutput::RequireBriefOpen]
 
+# Wrong. This recommends using the unsafe <>/<ARGV> operator.
+[-InputOutput::ProhibitExplicitStdin]
+
 # Depends on existing APIs, might break too much code. Enable per project.
 [-Modules::ProhibitAutomaticExportation]