Do any actions need to be performed on the Unix servers prior to the SSL certificate renewal on the Domain Controllers?
No, updating your SSL certificate on your AD domain controller will not affect QAS as it uses GSSAPI/Kerberos LDAP which eliminates the need for the distribution of SSL certificates to Unix clients.
For more information refer to Quest Solution SOL57421 - "How does QAS encrypt data? What encryption does QAS use?":