Revert "Install EPEL for repo_server role"

As EPEL is now deployed in the LXC cache and by the pip_install
role, this is no longer required.

This reverts commit 6106d6c.

Change-Id: I2441f881059cd942345f4a01cbd82c643263010d

tasks/repo_install.yml

@@ -20,15 +20,6 @@
   when:
     - ansible_pkg_mgr == 'apt'
 
-# NOTE: The pip_install role configures the RDO repository to be at a higher
-#       priority than EPEL. Packages from RDO will be preferred over EPEL.
-- name: Install EPEL repository
-  yum:
-    name: epel-release
-    state: "{{ repo_server_package_state }}"
-  when:
-    - ansible_pkg_mgr == 'yum'
-
 - name: Install repo server packages
   package:
     name: "{{ item }}"