Proxy fixes (#5869)

* Fix proxy and module_hotfixes

On CentOS 8 with proxy ansible render inline `proxy` and `module_hotfixes` options.

For example:

`proxy=http://127.0.0.1:3128module_hotfixes=True`

But expected result:

```
proxy=http://127.0.0.1:3128
module_hotfixes=True
```

* Use ini_file module for work with ini files

* Prevent duplicates proxy= option in /etc/yum.conf

Module `lineinfile` is weak, use most powerful module `ini_file` and add or remove `proxy=` when `http_proxy` is defined or not.

roles/bootstrap-os/tasks/bootstrap-centos.yml

@@ -42,15 +42,14 @@
     - not centos_fastestmirror_enabled
 
 - name: Add proxy to /etc/yum.conf if http_proxy is defined
-  lineinfile:
+  ini_file:
     path: "/etc/yum.conf"
-    regexp: "^proxy=.*$"
-    line: "proxy={{ http_proxy }}"
-    create: true
-    state: present
+    section: main
+    option: proxy
+    value: "{{ http_proxy | default(omit) }}"
+    state: "{{ http_proxy | default(False) | ternary('present', 'absent') }}"
+    no_extra_spaces: true
   become: true
-  when:
-    - http_proxy is defined
 
 - name: Gather host facts to get ansible_distribution_major_version
   setup: