Changes to Update a load balancer

added the required property allOf[subschema #2]/vms/items/maintenance_window_start_at to the response with the 200 status

added the required property allOf[subschema #2]/vms/items/boot_image to the response with the 200 status

added the new optional request property cert_enabled

added the optional property allOf[#/components/schemas/LoadBalancer]/cert_enabled to the response with the 200 status