Stop using pre-compiled wheels

We actually want to ensure users are able to use our roles outside of
openstack-infra. Since those users won't have wheel mirrors, disable
our jobs from using them too.

Change-Id: I50d8d5173869c6b69088f6ebad1234fd70135cb8
Signed-off-by: Paul Belanger <pabelanger@redhat.com>

tests/playbooks/pre.yaml

@@ -1,5 +1,12 @@
 - hosts: all
   tasks:
+    - name: Disable extra wheels mirror
+      become: yes
+      lineinfile:
+        dest: /etc/pip.conf
+        regexp: ^extra-index-url
+        state: absent
+
     - name: Bootstrap tox environment
       args:
         chdir: "{{ windmill_src_dir }}"