Draft: Federate metrics using VictoriaMetrics

The scope for this MR is to test if VictoriaMetrics could be a solution to federate metrics from various cluster. Once the victoria-metrics-cluster unit is enable the metrics will be fetched throught remote write api added in prometheus configuration. To visualize the metrics collection a new datasource will be added in grafana and data could be sorted by cluster label in order to identify the origin of metrics. Following link provide a good overview about this solution and comparing with another similar tool (thanos) : https://faun.pub/comparing-thanos-to-victoriametrics-cluster-b193bea1683.