Optional configuration for downloading ocp binary client from working cluster

[KatyT123]

Hi, I would like to ask you to create an optional configuration for xtf's users to download oc binary client from working openshift cluster as it was implemented in xtf 0.24.
i.e wget -c https://downloads-openshift-console.apps.jws-qe-j0eo.dynamic.xpaas/amd64/linux/oc.tar.

The reason is that we have issues with downloading the binary from the default mirror which is used in xtf 0.26 and issues when running the tests on clusters with candidate ocp versions as described in #491

[mnovak1]

@KatyT123 Is this issue still valid? Or was it caused by IPv6 issue on test machine?