feature(onprem): enable haproxy monitoring

[ralgozino]

enable metrics scraping from the haproxy loadbalancers and deploy the dashboards and alerts for haproxy from the monitoring module.

Note: I was unsure on setting some auth on the prometheus endpoint. Being that the 8405 port most likely will be accessible only from the inside I think that is enough. But let me know what you think.

Warning

This PR depends on the PR that adds the haproxy package to the monitoring module:

• feature: haproxy rules and dashboard. Enable scrapeConfigs. fury-kubernetes-monitoring#179

And it is also has been rebased on the following PR that introduces PrometheusAgent mode that we needed to consider:

• feat(monitoring): add remoteWrite to Prometheus and Prometheus Agent mode #228

[ralgozino]

setting this PR as draft. I'll rebase these changes on top of the PR #228 because we'll need to consider the cases introduced by that PR

[ralgozino]

I've rebased this PR to be branched from the changes introduced by #228 so we could consider the case when monitoring is in PrometheusAgent mode. Notice that you'll see the changes of #228 until it gets merged.

It is now ready for review.

[nutellinoit]

to be tested after merge