Similar to having a dedicated API node and to JSDSERVER-7992 (which is related to Assets admin tasks), it would be nice to be able to configure a node in the cluster to handle any indexing activity, even if those are triggered from other nodes in the cluster.

While, as of today, it is easy to set up an admin node in a cluster by just leaving it out of the rotation at the load balancer, the idea here would be actually to avoid the remaining nodes performing indexing tasks, by routing the indexing requests made through those to the designated admin/indexing node.