Removing the unused _prefix and _version variables.

[mbruzek]

According to @sdodson [0] and the sanity_checks.py file [1]

We don't need the _prefix or _version variables in 3.10, they are unused variables likely left over from trying to get 3.9 deployments working.

The sanity_checks.py file is a plugin that is supposed to fail if you are using these REMOVED_VARIABLES. I searched the logs for our deploy and do not see any messages related to this. The sanity_checks.py does not seem to be printing any errors in our deployments. It may be related to how we run OpenStack installs with the inventory/group_vars/OSEv3.yml file separate from the inventory.py file. Something to look into in the future.

[0] - (03:15:15 PM) mbruzek: Hi Scott. It looks like we define a lot of these REMOVED_VARIABLES. I am fixing them now, but wanted to verify with you. I know I don't need the "_prefix" and "_version". Do I need to replace it with "_image" or will the ose_reg /code compute the image? (03:16:09 PM) sdodson: you shouldn't to set any image prefixes or versions in 3.10

[1] - https://github.com/openshift/openshift-ansible/blob/master/roles/lib_utils/action_plugins/sanity_checks.py

[mbruzek]

In fact the sanity checks are being run and our automation always passes. Here is output from a build earlier today (where we had several REMOVED_VARIABLES):

TASK [Run variable sanity checks] ***************************************************************
task path: /home/cloud-user/openshift-ansible/playbooks/init/sanity_checks.yml:14
Friday 08 June 2018  15:29:47 -0400 (0:00:00.271)       0:00:29.191 ***********
ok: [master-1.scale-ci.example.com] => {
    "changed": false,
    "msg": "Sanity Checks passed"
}

Fix this!

[sdodson]

Oh, one note, if you're using these variables for 3.9 then you still need to set them. Otherwise LGTM

[mbruzek]

Thanks for the review Scott! I will keep that in mind if we ever go back to 3.9.