Remove dockerproject_.+_repo_.+ variables (#5662)

This 38688a4486 change replaces the
value for dockerproject_.+_repo_.+ docker variables but their new
value was previously defined in other variables. This change removes
the dockerproject_.+_repo_.+ docker variables in favor of the older
ones.

roles/container-engine/docker/tasks/main.yml

@@ -104,10 +104,10 @@
 - name: Configure docker repository on RedHat/CentOS/Oracle Linux
   yum_repository:
     name: docker-ce
-    baseurl: "{{ dockerproject_rh_repo_base_url }}"
+    baseurl: "{{ docker_rh_repo_base_url }}"
     description: "Docker CE Stable - $basearch"
     gpgcheck: yes
-    gpgkey: "{{ dockerproject_rh_repo_gpgkey }}"
+    gpgkey: "{{ docker_rh_repo_gpgkey }}"
     keepcache: "{{ docker_rpm_keepcache | default('1') }}"
     proxy: " {{ http_proxy | default('_none_') }}"
   when: ansible_distribution in ["CentOS","RedHat","OracleLinux"] and not is_atomic