Clean up pti-python-tarball python-branch-tarball

OpenStack's Python release jobs don't run tox, and don't install the
projects being packaged, not even in the branch tarball variants
these days. Remove the bindep, ensure-tox and collect-tox-logs roles
from pti-python-tarball and python-branch-tarball playbooks so that
the jobs using them can be more portable between distro versions
with less work. This should also make the jobs considerably faster.

Change-Id: Icc30a79f770ed78674354f6226d28907bab7eb1d

playbooks/pti-python-tarball/pre.yaml

@@ -1,7 +1,6 @@
 - hosts: all
   roles:
-    - bindep
+    # We use ensure-pip to make sure the wheel module is installed
     - ensure-pip
-    - ensure-tox
     - revoke-sudo
 

playbooks/python-branch-tarball/post.yaml

@@ -1,6 +1,5 @@
 - hosts: all
   roles:
-    - fetch-tox-output
     - fetch-python-sdist-output
 
   pre_tasks: