Update Prometheus client to 1.0.0

[burmanm]

The new Prometheus client isn't backwards compatible with our current implementation, so some changes are inevitable (and not just dependency change from 0.16.0 -> 1.0.0).

However, the old pre 1.0.0 implementation is not supported anymore and the new one should provide support for new native Prometheus histograms which I assume are a lot better than the current ones. So there might be some changes to how we output the metrics.

┆Issue is synchronized with this Jira Story by Unito