Revert "[cli] keeping 'copr mock-config' functionality"
    
    This reverts commit f12e62af234137c59862439872ad15a77283d873.
    
    Was discussed at:
    
    - https://pagure.io/copr/copr/pull-request/179
    - https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org/message/BTEDOVOWB4ARAY3Q3C4VVMFWTAMBUFON/
    - https://pagure.io/copr/copr/issue/223
    
    The mailing list thread outlines that the mock config generator
    should be only kept in copr-rpmbuild. That's why this deprecation
    happened.