Do not test mysql_variables modes persist and persist_only on mariadb

Those modes do not exist on mariadb. See https://mariadb.com/kb/en/set/

tests/integration/targets/test_mysql_variables/tasks/mysql_variables.yml

@@ -359,7 +359,9 @@
 
         - include: assert_var.yml changed=true output={{ result }} var_name={{ set_name }} var_value='{{ def_val }}'
 
-      when: mysql_version is not version('8.0', '<')
+      when:
+        - mysql_version is version('8.0', '>=')
+        - install_type == 'mysql'
 
     # Bugfix of https://github.com/ansible/ansible/issues/54239
     # - name: set variable containing dot