I have tested this and it does not work through ambari.
You can change it in the cfg located in /etc/zookeeper/conf and start zookeeper manually but if you start it in ambari it is overwritten.
I know where this comes from but I don’t think it’s as easy as “just modifying” it there, let me check and get back to you.
You could create a symbolic link or mount your drive there as a prospective workaround?
I’ll let you know,