PLT-6080 moving clustering to memberlist (#6499)

* PLT-6080 adding cluster discovery service

* Adding memberlist lib

* Adding memberlist lib

* WIP

* WIP

* WIP

* WIP

* Rolling back config changes

* Fixing make file

* Fixing config for cluster

* WIP

* Fixing system console for clustering

* Fixing default config

* Fixing config

* Fixing system console for clustering

* Tweaking hub setting

* Bumping up time

* merging vendor dir

* Updating vendor dir

* Fixing unit test

* Fixing bad merge

* Remove some testing code

* Moving comment

* PLT-6868 adding db ping retry

* Removing unused loc strings

* Adding defer to cancel

api/context.go

@@ -150,9 +150,6 @@ func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	w.Header().Set(model.HEADER_REQUEST_ID, c.RequestId)
 	w.Header().Set(model.HEADER_VERSION_ID, fmt.Sprintf("%v.%v.%v.%v", model.CurrentVersion, model.BuildNumber, utils.ClientCfgHash, utils.IsLicensed))
-	if einterfaces.GetClusterInterface() != nil {
-		w.Header().Set(model.HEADER_CLUSTER_ID, einterfaces.GetClusterInterface().GetClusterId())
-	}
 
 	// Instruct the browser not to display us in an iframe unless is the same origin for anti-clickjacking
 	if !h.isApi {