Drop generic/openshift.ks

After commit 445b9d2b585de568981b3a2ef89c99a43c839a4a, there is little
difference between the regular openshift.ks and generic/openshift.ks, so
drop the latter as well as the generic/converter script and Makefile rule
that generated it.

The only difference in generic/openshift.ks was that it had an
additional call to configure_console_msg, which adds some information to
/etc/issue.  Commit 74847cb06409e77d5ff865583f615da83898bd94 added this
call to openshift.ks, and so generic/openshift.ks ended up with two
calls to configure_console_msg.  By deleting generic/openshift.ks, this
commit resolves that issue.

This commit also comments out the call to configure_console_msg when
generating openshift-amz.sh.