feat: support location label in globally evaluated regional aggregation

feat: support location label in globally evaluated regional aggregation

This adds the location label to both regional aggregation sets. This is required, because we use these aggregation sets to build the regional dashboards. So including the label here will correctly separate the series on the graph including the location label.

We need to support the location label because the Thanos-sidecar overwrites the region label present on metrics with the external label advertised by Prometheus. See gitlab-com/gl-infra/scalability#3392 (comment 1852103750) for more information about this.

We will probably not need to add the location label in mimir, for the metrics that are remote-written from stackdriver-exporter, this is already correct. But we might still have to add it to mimir for metrics collected from the regionally deployed application itself. We will figure do that, if needed, in gitlab-com/gl-infra/scalability#2722 (closed).

To support a globally evaluated, but regionally deployed service, we generate the regional recording rules from source metrics in Thanos. This is similar to what we already do in Mimir.

This is required for gitlab-com/gl-infra/platform/runway/team#185 (closed)