I figured it out...
the ansible module uses the same thing sysprep uses.In this case the MachineObjectOU is the parameter you can add. Its not on any ansible documentation either.
customization:
domainadmin: "{{ joinDomainUser }}"
domainadminpassword: "{{ joinDomainPassword }}"
joindomain: "{{ joinDomainName }}"
MachineObjectOU: "{{ domainOuPath }}"