Fix image build checks missing setuptools

Use apt to install python3-pip, and use pip3 in event system has
both pip2 and pip3 installed. Use apt to install setuptools for
Ansible's consumption.

Change-Id: Id6a82fef4ae1fc6f9ed754f192f0e40c55f92eb2
Signed-off-by: Alexander Hughes <Alexander.Hughes@pm.me>

tools/gate/playbooks/airship-porthole-gate-runner.yaml

@@ -12,6 +12,19 @@
 
 - hosts: primary
   tasks:
+    - name: install python
+      apt:
+        name: "{{ item }}"
+        allow_unauthenticated: True
+      with_items:
+        - python3-pip
+        - python3-setuptools
+      become: true
+    - name: ensure tox is present
+      pip:
+        name: tox
+        executable: pip3
+      become: true
     - name: Run gate scripts
       include_role:
         name: osh-run-script

tools/gate/playbooks/docker-image-build.yaml

@@ -47,10 +47,12 @@
             allow_unauthenticated: True
           with_items:
             - docker-ce
-            - python-pip
+            - python3-pip
+            - python3-setuptools
         - pip:
             name: docker
             version: 2.7.0
+            executable: pip3
         # NOTE(SamYaple): Allow all connections from containers to host so the
         # containers can access the http server for git and wheels
         - iptables: