Fix selectors for thanos-staging SLIs

Fix labels for thanos-staging SLIs

These metrics don't get the correct type label everywhere on ingestion, so let's ignore that for now and just rely on the namespace label globally.

Some of the storegateway, ruler and compactor metrics also have different formats than production. This fixes those to the correct ones so we have some rules. We might want to update these to match what we currently have in production when we deploy a new rules.

For https://gitlab.com/gitlab-com/gl-infra/reliability/-/issues/24423