add support of rancher 2.14.x in sylva

as the changes for rancher 2.14 are being reverted in !6891 (merged) as per discussions in !6891 (comment 3305318199) and workaround for relaxing the rancher Helm chart kubeVersion constraint was implemted in !7723 (merged), as soon as we have a fix for #4003 (closed) (upstream bug https://github.com/rancher/rancher/issues/54950), we'll proceed with the integration of rancher 2.14.x