Remove remaining Thanos components

After migrating to Mimir, we opted to keep Thanos around for Historical data as this was simpler than migrating and risking overlapping series, as well as added the benefit of not needing to concern ourselves with complicated proxy logic to have backwards compatibility with old issue/incident links.

Originally we looked at keeping this around for up to a year as a loose timeline, but I think we should consider moving this to a state where we can offline the infrastructure. We will keep the data and provide a process for accessing it in the event someone would like to be able to reference of the historical time series.

This will help reduce some unnecessary cost.