install-ansible: remove stub install for ARA

The current version of ARA doesn't depend on the "ansible" package any
more, so we don't need this fake stub package installed to fool it.
Remove this workaround.

Change-Id: I9330a22650204464b0b677fca06deec494731641

playbooks/roles/install-ansible/tasks/install_ansible_stub.yaml

@@ -1,22 +0,0 @@
-- name: Create build dir
-  tempfile:
-    state: directory
-    suffix: fake-ansible
-  register: _build_dir
-
-- name: Install fake setup.py
-  blockinfile:
-    create: yes
-    path: '{{ _build_dir.path }}/setup.py'
-    block: |
-      import setuptools
-
-      setuptools.setup(name="ansible",
-                 url="http://fake.com",
-                 maintainer="nobody@nobody.com",
-                 version="2.9.0",
-                 description="Fake ansible")
-
-- name: Install stub ansible
-  pip:
-    name: '{{ _build_dir.path }}'

playbooks/roles/install-ansible/tasks/main.yaml

@@ -20,28 +20,18 @@
     _install_ansible_state: latest
   when: install_ansible_version == 'latest'
 
-# Since Ansible 2.10 (~2020-08) the devel core package is split into
-# "ansible-base".  The PyPi the package "ansible" has everything in it
-# (the so called Ansible Community Distribution) but we specifically
-# want to test against devel.  However, ARA still depends on the
-# "ansible" package -- but we like ARA, because we can see the nested
-# runs with it.  To to keep ARA but avoid it bringing in either an old
-# version of Ansible, or the ACD, install a dummy package.
+# From Ansible 2.10 >= most of the fun stuff is in collections.  Clone
+# our required collections here.  Note this is only for our testing of
+# the devel branch; if we're using a release we use the Ansible
+# distribution package which bundles all this.
+#
+# TODO(ianw): we should add these to zuul and link the speculative
+# copies into ansible, then we could test changes in the collections!
 - name: Check if running devel branch
   set_fact:
     _install_ansible_from_devel: true
   when: '"github.com/ansible/ansible" in install_ansible_name'
 
-- name: Setup Ansible stub for post 2.10 compat
-  include_tasks: install_ansible_stub.yaml
-  when: _install_ansible_from_devel is defined
-
-# From Ansible 2.10 >= most of the fun stuff is in collections.  Clone
-# our required collections here.  Note, in production, we use ACD
-# which bundles most of this.
-#
-# TODO(ianw): we should add these to zuul and link the speculative
-# copies into ansible, then we could test changes in the collections!
 - name: Install Ansible collections
   include_tasks: install_ansible_collection.yaml
   when: _install_ansible_from_devel is defined