The value of the field must be in 0, 1. When the ratio of the count
of healthy backend endpoints in a zone to the count of backend
endpoints in that same zone is equal to or above this threshold, the
load balancer distributes new connections to all healthy endpoints in
the local zone only. When the ratio of the count of healthy backend
endpoints in a zone to the count of backend endpoints in that same
zone is below this threshold, the load balancer distributes all new
connections to all healthy endpoints across all zones.