refactor: Move vars to appropriate group_var files

We parameterized a few tasks in the cheaha.yml and put the vars in
group_vars/all so that the existing knightly builds won't break.
We added values required for the CoD deploy in group_vars/proxy. Now if
we put the proxy nodes in proxy group they will inherit values meant for
CoD deploy which is not desired in production.
We later realized that the appropriate file is group_vars/knightly and
it gives flexibility to put proxy nodes in knightly group to override
the vars meant for CoD in group_vars/all.