incubator/consul is deprecated

Use HashiCorp's Official Helm Chart (https://github.com/hashicorp/consul-helm), which is already included in the Hubs. See Consul docs (https://www.consul.io/docs/k8s/installation/overview) for installation instructions.

Note: incubator/consul was previously moved from incubator to stable before a deprecated version was published to this helm repo. Therefore, in order to remove the old versions from aggregators such as Helm Hub (https://hub.helm.sh) and Artifact Hub (https://artifacthub.io/) we have re-added this placeholder deprecated chart. See https://github.com/helm/charts/issues/23128 for further details.
