Add ignore_none_type to config_template

The .cnf files can have valueless options present.
This commit ensures that these valueless options are not ignored

Addtionally, my.cnf overrides are added to the variable overrides
test file to ensure that the my.cnf file can run through the
config_template engine properly.

Change-Id: I8b09c2520c84bb43353b4c56bac157259f71b041
Closes-Bug: #1693234

releasenotes/notes/fix-mysql-overrides-e5362ae15c657214.yaml

@@ -0,0 +1,8 @@
+---
+fixes:
+  - |
+    Mysql cnf files can now be properly overridden. The config_template
+    module has been extended to support valueless options, such as those that
+    are found in the my.cnf file(i.e. `quick` under the `mysqldump` section).
+    To use valueless options, use the `ignore_none_type` attribute of the
+    config_template module.

tasks/galera_post_install.yml

@@ -45,6 +45,7 @@
     mode: "0644"
     config_overrides: "{{ item.config_overrides }}"
     config_type: "{{ item.config_type }}"
+    ignore_none_type: False
   with_items:
     - src: my.cnf.j2
       dest: "{{ galera_etc_conf_file }}"

tests/galera_server-overrides.yml

@@ -26,3 +26,8 @@ galera_server_old_package:
   suse:
     galera_mariadb_server_package: "mariadb"
     galera_repo_url: "http://download.opensuse.org/repositories/server:/database/openSUSE_Leap_{{ ansible_distribution_version }}"
+
+# Testing my.cnf overrides
+galera_my_cnf_overrides:
+  sst:
+    sst-initial-timeout: 600