copr: builder: drop mock.cfg.j2

We keep updating the file in copr-rpmbuild; this hack was added
(perhaps, original commit doesn't cite it) to work-around rhbz#1580435,
and that is not an issue nowadays in mock.

roles/copr/backend/files/provision/files/copr-rpmbuild/mock.cfg.j2

@@ -1,44 +0,0 @@
-include('/etc/mock/{{ chroot }}.cfg')
-
-config_opts['root'] = '{{ task_id }}'
-
-config_opts['nspawn_args'] = ['--capability=cap_ipc_lock']
-
-{% if buildroot_pkgs %}
-config_opts['chroot_additional_packages'] = '{{ buildroot_pkgs| join(" ") }}'
-{% endif %}
-
-{% if enable_net %}
-config_opts['rpmbuild_networking'] = True
-config_opts['use_host_resolv'] = True
-{% else %}
-config_opts['rpmbuild_networking'] = False
-config_opts['use_host_resolv'] = False
-{% endif %}
-
-config_opts['use_bootstrap_container'] = {{ 'True' if use_bootstrap_container else 'False' }}
-
-{% if use_bootstrap_container %}
-config_opts['bootstrap_chroot_additional_packages'] = []
-config_opts['bootstrap_module_enable'] = []
-config_opts['bootstrap_module_install'] = []
-{% endif %}
-
-{% if repos %}
-config_opts['{{ pkg_manager_conf }}.conf'] += """
-{% for repo in repos %}
-[{{ repo["id"] }}]
-name='{{ repo["name"] }}'
-baseurl={{ repo["baseurl"] }}
-gpgcheck=0
-enabled=1
-skip_if_unavailable=1
-metadata_expire=0
-cost=1
-best=1
-{%- if "priority" in repo %}
-priority={{ repo["priority"] }}
-{%- endif %}
-{% endfor %}
-"""
-{% endif %}