Move to Ansible 3.4.0 (#7672)

* Ansible: move to Ansible 3.4.0 which uses ansible-base 2.10.10

* Docs: add a note about ansible upgrade post 2.9.x

* CI: ensure ansible is removed before ansible 3.x is installed to avoid pip failures

* Ansible: use newer ansible-lint

* Fix ansible-lint 5.0.11 found issues

* syntax issues
* risky-file-permissions
* var-naming
* role-name
* molecule tests

* Mitogen: use 0.3.0rc1 which adds support for ansible 2.10+

* Pin ansible-base to 2.10.11 to get package fix on RHEL8

roles/etcd/tasks/gen_certs_script.yml

@@ -21,6 +21,7 @@
   template:
     src: "openssl.conf.j2"
     dest: "{{ etcd_config_dir }}/openssl.conf"
+    mode: 0640
   run_once: yes
   delegate_to: "{{ groups['etcd'][0] }}"
   when: