Just starting up services for Snuba or Sentry migrations takes up to a minute sometimes and we do this even when there are no migrations, just because one of the Sentry or Snuba migrations change. This patch splits the caches up so only the necessary one runs, saving further time. It also uses the `LATEST_TAG` as the cache key for upgrade tests as the image versions or data will never change for a certain tag once it is release.
I think we split these actions in the past due to some lack of options for them to work together properly. Right now looks like `bootstrap` would automatically migrate and propagates the `force` flag.
