Rewrite `Collect Prometheus metrics with Sensu` to update it

[asachs01]

Description

Category

This is an issue with:

• [ ] errata (error in doc content)
• [ ] new doc (requires a completely new doc)
• [x] update (add missing or refresh existing content)
• [ ] improvement (improve docs content or format)

Affected pages

https://docs.sensu.io/sensu-go/latest/observability-pipeline/observe-schedule/prometheus-metrics/#create-a-pipeline-that-includes-the-influxdb-handler

Changes needed

This article is a bit outdated, given that the agent can natively collect Prometheus metrics without the need for the Prometheus collector asset. It's also worth noting that many of our check now natively generate metrics in Prometheus plaintext, which eliminates the need set up Prometheus, thus simplifying the overall configuration.

[asachs01]

Noting here that there's a companion page in https://docs.sensu.io/sensu-go/latest/plugins/featured-integrations/prometheus/ that mentions the prometheus collector. We should eliminate the collector as part of the featured integrations page, given that it's pretty well deprecated.