Revert "Ensure virtualenv/pip are installed on centos"

This seems to be failing in all role tests, needs investigation.

This reverts commit 0a11800302.

Change-Id: If84d45acd2e49b4f4fd65d86670b6ac2621c3a70

vars/redhat-7.yml

@@ -22,6 +22,8 @@ openstack_host_module_file: /etc/modules-load.d/openstack-ansible.conf
 
 openstack_host_sysstat_cron_mode: '0600'
 
+openstack_host_use_distro_pip: false
+
 ## Kernel modules loaded on hosts
 openstack_host_kernel_modules:
   - name: 8021q
@@ -48,9 +50,7 @@ openstack_host_kernel_modules:
   - name: vhost_net
 
 ## Base packages
-_openstack_host_distro_packages:
-  - python-virtualenv
-  - python-pip
+_openstack_host_distro_packages: []
 
 ## Bare metal base packages
 _openstack_host_metal_distro_packages: