add strategy mitogen_linear when installed mitogen (#5985)

* add strategy mitogen_linear when installed mitogen

* add small docs

Rename playbook file

The raw action executes as a regular Mitogen connection, which requires Python on the target, so add strategy: linear to bootstrap-os role playbook.

* add mitogen to  CI test
fix typo

* enable mitogen test on deploy-part1 tests
change version from master to release
download tar.gz archive

* run all CI tests with mitogen

* disable mitogen with upgrade CI tests

* enable mitogen on CI tests via env vars

* disable mitogen on CI test by default, enable on some different OS

* disable mitogen CI test on centos8
(get error  /usr/bin/python: No such file or directory)

mitogen.yml

@@ -0,0 +1,42 @@
+---
+- name: Check ansible version
+  import_playbook: ansible_version.yml
+
+- hosts: localhost
+  strategy: linear
+  vars:
+    mitogen_version: 0.2.9
+    mitogen_url: https://github.com/dw/mitogen/archive/v{{ mitogen_version }}.tar.gz
+    ansible_connection: local
+  tasks:
+    - name: Create mitogen plugin dir
+      file:
+        path: "{{ item }}"
+        state: directory
+      become: false
+      loop:
+        - "{{ playbook_dir }}/plugins/mitogen"
+        - "{{ playbook_dir }}/dist"
+
+    - name: download mitogen release
+      get_url:
+        url: "{{ mitogen_url }}"
+        dest: "{{ playbook_dir }}/dist/mitogen_{{ mitogen_version }}.tar.gz"
+        validate_certs: true
+
+    - name: extract archive
+      unarchive:
+        src: "{{ playbook_dir }}/dist/mitogen_{{ mitogen_version }}.tar.gz"
+        dest: "{{ playbook_dir }}/dist/"
+
+    - name: copy plugin
+      synchronize:
+        src: "{{ playbook_dir }}/dist/mitogen-{{ mitogen_version }}/"
+        dest: "{{ playbook_dir }}/plugins/mitogen"
+
+    - name: add strategy to ansible.cfg
+      ini_file:
+        path: ansible.cfg
+        section: defaults
+        option: strategy
+        value: mitogen_linear