switch MySQL 8 to use native password to avoid playbook incompatibility

salt/mysql/etc/my.cnf

@@ -29,3 +29,6 @@ symbolic-links=0
 
 log-error=/var/log/mysql/mysqld.log
 pid-file=/var/run/mysqld/mysqld.pid
+
+# Switch back to the native password module so that playbook can connect
+default_authentication_plugin=mysql_native_password