v2.1: Report ConsumeWorkerMetrics on 20ms interval (backport of #4708)

[mergify]

Problem

• 1s interval is too large to report worker metrics
• reporting on a 20s interval, many times per slot, gives us a picture of when and how things are processed as our leader slots progress

Summary of Changes

• Report ConsumerWorkerMetrics on a 20ms interval
• Gives us really great charts like this, showing how quickly we're able to fill blocks:
  

Fixes #

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This is an automatic backport of pull request #4708 done by [Mergify](https://mergify.com).

[t-nelson]

the idea here is to dos influx?

[alessandrod]

the idea here is to dos influx?

If you won't shut it down, we will.

Metrics are batched so it's not like this does a POST every 20ms. The number of requests stays the same, the payload grows slightly larger. The metric is only reported when the workers have done work, so only by leaders during their leader slots.

[t-nelson]

the payload grows slightly larger

50x? welcome to the devops team!