Partially revert "playbook: Install slapos.node from shacache"

This partially reverts commit dbc26026.

Despite of locally installing slapos.node in some cases, the repository is
required for other tasks (like installing re6st-node).

playbook/roles/repository/tasks/main.yml

@@ -96,6 +96,10 @@
     apt_repository: repo='deb {{ base_open_build_url }}/xUbuntu_17.10/ ./' state=present
     when: ansible_distribution == "Ubuntu" and ansible_distribution_version == "17.10"
 
+  - name: Install CentOS 7 Repository
+    get_url: url=http://download.opensuse.org/repositories/home:/VIFIBnexedi/CentOS_7/home:VIFIBnexedi.repo dest=/etc/yum.repos.d/slapos.repo mode=0440
+    when: ansible_distribution == "CentOS" and ansible_distribution_major_version == "7"
+
   - name: Install CentOS 7 RPM Key
     # workarounded with https://github.com/marbu/ansible-modules-core-issue-1853-reproducer/commit/41727b465533717015d8d55904c5a102fe248bc4
     # for https://github.com/ansible/ansible-modules-core/issues/1853