Not that i know of - but if i understand AJP properly, there is no need to implement it as you can perform essentially the same functionality by using Tableau worker.
What is the goal? Vusi is correct, Tableau Server can manage its own load balancing via workers.
An alteration to Tableau Server's Apache mod_proxy or other settings would not be supported.
This post is a bit old, but I would require AJP functionality to be able to put an Apache instance using mod_jk in front of Tableau Server or even IIS in front of Tableau Server using BonCode AJP Connector.
This way it would be in line with our existing architecture of exposing Web Application/Service functionality.