New implementation of firehose_exporter

[ArthurHlt]

This PR is associated to PR cloudfoundry/firehose_exporter#63 on firehose_exporter.
Please see this pull request for more context.

Here, it will only change dashboards consequently to the change of http_start_stop, set correct ctl for new firehose exporter and fix previous operator for firehose.

Dashboard latency include new panels which look like this a the end:

[benjaminguttmann-avtq]

Hi @ArthurHlt had a look at this one and there are a couple things I want to mention,

as I read in the firehose_exporter it is fully "retro" compatible but we modify the dashboards to only work with the new metrics, maybe we should introduce a version 2 of the dashboards handling the new metrics. In this case it might be worth checking if we can combine it with the improvements in #423 by @thehandsomezebra .

So we can get both in there.

I think we have some alerts relying on the firehose_http_start_stop_requests, do we need to adjust them as well?

I think this part of the README needs to get adjusted as well, right? As we need some additional certificate now?

In addition, I am wondering if we should add some instructions, ops files to help people that still rely on the 'retro' compatible version.

[thehandsomezebra]

Thanks @benjaminguttmann-avtq for pinging me on this one.
I checked this out, and I think that @ArthurHlt 's PR would need just a couple adjustments to not conflict with my PR #423 AND still be backwards compatible..

Here's my thoughts:

• cf_apps_latency.json <-- I made a v2 on this with a couple adjustments versus v1, so this might be the only conflicting file versus my PR. @benjaminguttmann-avtq -- This could be changed to a v3, no conflicts with my PR.
• cf_apps_requests.json <-- This could be changed to a new v2 dashboard, no conflicts with my PR.
• prometheus_firehose_exporter.json <-- This could be changed to a v2, no conflicts with my PR.

I do have concerns about the other files like jobs/firehose_exporter/spec -- If you are removing properties in the spec file, I'm curious on how this would be backwards compatible? At what point would the firehose_exporter PR be classified as breaking changes..?

[psycofdj]

closing in favor of #461