mysql modules: fix failing when \!include_dir is in .my.cnf

tests/integration/targets/test_mysql_db/tasks/config_overrides_defaults.yml

@@ -3,6 +3,7 @@
     config_file: "/root/.my1.cnf"
     fake_port: 9999
     fake_host: "blahblah.local"
+    include_dir: "/root/.my.cnf.d"
 
 - name: Create custom config file
   shell: 'echo "[client]" > {{ config_file }}'
@@ -10,6 +11,15 @@
 - name: Add fake port to config file
   shell: 'echo "port = {{ fake_port }}" >> {{ config_file }}'
 
+- name: Create include_dir
+  file:
+    path: '{{ include_dir }}'
+    state: directory
+    mode: '0777'
+
+- name: Add include_dir
+  shell: 'echo "!include_dir {{ include_dir }}" >> {{ config_file }}'
+
 - name: Create database using fake port to connect to, must fail
   mysql_db:
     login_user: '{{ mysql_user }}'