install-ansible: remove testinfra version install workaround

This was added with 3cd8cd0765 but
ansible-core is a package now.  We can remove this workaround.

Change-Id: Ide1f3bbfe8887315a9f574bb1c19bf3234f58686

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

@@ -32,23 +32,6 @@
     _install_ansible_from_devel: true
   when: '"github.com/ansible/ansible" in install_ansible_name'
 
-# Since ~2020-11 ansible renamed "ansible-base" to "ansible-core".
-# Unfortunately, ansible-base and ansible-core can not live happily
-# together.  For testinfra, our tox role pre-installs the requirements
-# from tox.ini (ansible-base) but then tries to install siblings (the
-# checked out ansible tree, now trying to install the "ansible-core"
-# package).  There is no working "ansible-core" package on PyPi, so
-# for now we have to switch this out in the tox.ini for the -devel job
-# to work.  We can remove this when "ansible-core" is published at an
-# appropriate version on PyPi; at that point the checked-out tree can
-# override the package in the testing tox venv.
-- name: Override ansible-base tox install
-  when: '"github.com/ansible/ansible" in install_ansible_name'
-  lineinfile:
-    path: /home/zuul/src/opendev.org/opendev/system-config/tox.ini
-    regexp: '^  ansible-base # see install-ansible/tasks/main\.yaml$'
-    line:   '  ansible-core'
-
 - name: Setup Ansible stub for post 2.10 compat
   include_tasks: install_ansible_stub.yaml
   when: _install_ansible_from_devel is defined

tox.ini

@@ -37,7 +37,7 @@ commands = sphinx-build -W -E -b html doc/source doc/build/html
 
 [testenv:testinfra]
 deps =
-  ansible-base # see install-ansible/tasks/main.yaml
+  ansible-core
   pytest-html # MPL-2.0
   pytest-testinfra>=6.0.0
   selenium