title: Remove stale data from exporting endpoint
body: <p>We've noticed huge CPU and RAM usage by our Prometheus instance and are looking into ways of lowering this. </p>
  
  <p>Some of the data we expose has an <code>ApplicationVersion</code> label attached to it. Each time we release a new version (which happens a few times/week), every metric will basically be duplicated because of this. Once all servers have this new version and we don't rollback, this <code>ApplicationVersion</code> should never occur again.</p>
  
  <p>Is it sensible to have a cleanup job in our exporter to remove this data? </p>