refactor: Remove tests for /metrics endpoint

[lenny-goodell]

This enpoint is being removed in edgexfoundry/edgex-go#4311 and future PRs for App and Device SDKs

Signed-off-by: Leonard Goodell [email protected]

If your build fails due to your commit message not passing the build checks, please review the guidelines here: https://github.com/edgexfoundry/edgex-go/blob/main/.github/Contributing.md

PR Checklist

Please check if your PR fulfills the following requirements:

• I am not introducing a breaking change (if you are, flag in conventional commit message with BREAKING CHANGE: describing the break)
• I am not introducing a new dependency (add notes below if you are)
• I have added unit tests for the new feature or bug fix (if not, why?)
• I have fully tested (add details below) this the new feature or bug fix (if not, why?)
• I have opened a PR for the related docs change (if not, why?)

Testing Instructions

New Dependency Instructions (If applicable)

[cherrycl]

LGTM