Remove "Stage" variable

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

deploy/grafana-dashboard/queries/environment-ids.flux

@@ -1,7 +1,6 @@
 from(bucket: "poseidon")
   |> range(start: -1y)
   |> filter(fn: (r) => r["_measurement"] == "poseidon_environments")
-  |> filter(fn: (r) => (not exists r.stage) or contains(value: r["stage"], set: ${stages:json}))
   |> keep(columns: ["id"])
   |> distinct(column: "id")
   |> keep(columns: ["_value"])