this patch adds two new related features. first, it removes the
requirement that all monitor deployments be pinned to nodes using node
selector. this is allowed when not using host networking and when PVC
storage is used. the second feature introduced in this patch is the
elimination of the Rook scheduler for placing monitors that continue to
use the node selector by using canary pods to that are scheduled by k8s,
after which Rook uses the scheduling results to pin the monitors to
nodes.
fixes: #3667
Signed-off-by: Noah Watkins <noahwatkins@gmail.com>