Add `env` label to promSource aggregation
Add env
label to promSource aggregation
This adds the env
label to the promSource aggregation. We select for
this on dashboards and we use this aggregation set for the services
evaluated in Thanos.
This shouldn't matter for the services evaluated in Prometheus,
because those already have the env
label anyway because of the
prometheus instance they come from.
Another piece in https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/23722