Change in Interval in the s3 plugin from int to float64

[linuxdynasty]

• Currently all counters return a +Inf and this is due to the fact that we are
  not passing Interval in server.go. Also in s3.go, interval was set to int instead
  of float64.
• Update csv_test.go to include tests when passing an Interval of 0.

Summary

As of right now any samplers.CounterMetric has a divide by 0 error which reports back as +Inf. This PR will fix that error for the S3 Plugin and the Localfile plugin. I also updated the tests in csv_test.go and s3_tests.go to check for +Inf.

Motivation

Counters were producing +Inf

Test plan

I updated tests in csv_test.go and s3_tests.go

Rollout/monitoring/revert plan

---

This change is 

[stripe-ci]

Gerald Rule: Copy Observability on Veneur, Unilog, Falconer pull requests

cc @stripe/observability
@stripe/observability-stripe

[linuxdynasty]

Is there anything further that the stripe team needs me to do for this PR request? I have the other PR #758 for updating how AWS credentials are handled and I will have 2 more PR requests that depend on these 2 being merged in.

[linuxdynasty]

I am using Veneur plugins heavily and I would rather not host a local version of Veneur for too long. Could someone let me know if this PR is missing something? As of right now, the S3 plugin is not working without this fix.

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you all sign our Contributor License Agreement before we can accept your contribution.
1 out of 2 committers have signed the CLA.

✅ linuxdynasty
❌ Allen Sanabria

---

Allen Sanabria seems not to be a GitHub user. You need a GitHub account to be able to sign the CLA. If you have already a GitHub account, please add the email address used for this commit to your account.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}