releasenotes: Remove package install

The vast majority of changes to enable running releasenotes without
installating of the package itself are merged. Remove the package
install now. Note that install-if-python is the proper role for this,
the previous setting was a noop.

The remaining few changes can merge at any time, projects had enough
time.

See also
http://lists.openstack.org/pipermail/openstack-dev/2017-November/124815.html

Needed-By: I225d73a2f9321329b34a282e08aea6773622df5b
Change-Id: I6d461a69537d3f7dd44e9b9877f652df656eedd8

playbooks/releasenotes/pre.yaml

@@ -7,6 +7,4 @@
       doc_building_packages:
         - sphinx
         - reno
-      # TODO(jaegerandi): Remove once all repos are fixed.
-      install_package: yes
     - revoke-sudo

playbooks/releasenotes/run.yaml

@@ -1,4 +1,6 @@
 - hosts: all
   roles:
-    - install-if-python
+    - role: install-if-python
+      # Releasenotes do not need the package itself to be installed
+      install_package: false
     - build-releasenotes