ensure-pip: install from EPEL for Python 2

On CentOS 7, the python-pip package comes from EPEL.  CentOS 8 and
Fedora don't have python-pip so it's safe to switch this to "yum" and
then we can use enablerepo.

Change-Id: I267f082b2db4e501299226f0033b5d940752d931

roles/ensure-pip/tasks/RedHat.yaml

@@ -9,11 +9,12 @@
   become: yes
 
 - name: Install Python 2 pip
-  package:
+  yum:
     name:
       - python-pip
       - python-setuptools
       - python-virtualenv
     state: present
+    enablerepo: epel
   become: yes
   when: ensure_pip_from_packages_with_python2