Decouple reconciler from the node manager

Reconciler currently depends on NodeManager to perform health checks. This commit decouples the reconciler from node manager to allow for alternative health checking implementations. Additionally, this reduces the surface of the interface and allows reconciler to only depend on the health information it needs without having to know about the primary.

This decoupling is necessary to hook up the per repository elector stack. 2d1c5b1e

Related to #3133 (closed)