openshift-amz.sh: Fix generation

Make sed command in the rule that generates amazon/openshift-amz.sh disable
the configuration of the RHEL repo, as intended.  This rule has been broken
since commit 8457439d88003566a5a4c907f492789db4dd10e6, which added
whitespace that broke the regex match in the sed command.

Make the same change to the other sed commands in the same rule to make
them resilient in case of other whitespace changes.

Regenerate openshift-amz.sh.