Update pip3 role to install from get-pip.py

Our base images have pip pre-installed from get-pip. This means
that the installation of pip and virtualenv from distro packages
in the ansible is misleading.

Update the role to match reality.

Change-Id: I500b14f9f9df00b6e0c4f152f8b4c7faa1bb94d4

playbooks/roles/pip3/tasks/main.yaml

@@ -1,6 +1,26 @@
-- name: Install pip and virtualenv
+- name: Remove pip and virtualenv packages
   package:
     name:
       - python3-pip
       - python3-virtualenv
-    state: present
+    state: absent
+
+- name: Download get-pip.py
+  command: wget https://bootstrap.pypa.io/get-pip.py
+  args:
+    chdir: /var/lib
+    creates: /var/lib/get-pip.py
+
+- name: Install pip
+  command: python3 /var/lib/get-pip.py
+  args:
+    creates: /usr/local/bin/pip3
+
+- name: Install latest pip and virtualenv
+  pip:
+    name: "{{ item }}"
+    state: latest
+    executable: pip3
+  loop:
+    - pip
+    - virtualenv