Revert "Fix ilm metric labels (prometheus-community#677)"

This reverts commit a5f33bb.

Author: jaimeyh

collector/ilm_status.go

@@ -79,7 +79,7 @@ func NewIlmStatus(logger log.Logger, client *http.Client, url *url.URL) *IlmStat
 			Desc: prometheus.NewDesc(
 				prometheus.BuildFQName(namespace, subsystem, "status"),
 				"Current status of ilm. Status can be STOPPED, RUNNING, STOPPING.",
-				[]string{"operation_mode"}, nil,
+				ilmStatuses, nil,
 			),
 			Value: func(ilm *IlmStatusResponse, status string) float64 {
 				if ilm.OperationMode == status {