Renew registrar-registry certificate

[h-m-f-t]

Issue description

The registrar-registry certificate expires in late October. Let's renew it.

Acceptance criteria

• [ ] Review documentation for cert generation and create the cert
• [ ] Update the certificate in the registry admin portal.
• [ ] Confirm with Cloudflare in our shared Slack channel that all systems are go

Additional context

No response

Links to other issues

No response

[h-m-f-t]

@abroddrick can you update the documentation anchor above and add a link? Then we'll remove refinement.