Remove "Stage" variable

as we will use distinct Influx and Grafana instances for the different stages/environments.

deploy/grafana-dashboard/queries/used-runner.flux

@@ -2,7 +2,6 @@ from(bucket: "poseidon")
   |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
   |> filter(fn: (r) => r["_measurement"] == "poseidon_used_runners")
   |> filter(fn: (r) => r["_field"] == "count")
-  |> filter(fn: (r) => (not exists r.stage) or contains(value: r["stage"], set: ${stages:json}))
   |> group(columns: ["stage"], mode:"by")
   |> keep(columns: ["_value", "_time", "stage"])
   |> aggregateWindow(every: duration(v: int(v: v.windowPeriod) * 5), fn: mean, createEmpty: false)