Fix Metrics cfg option naming typo

[NickMeves]

#1163

How Has This Been Tested?

Unit Tests & contrib/local-environment manual testing

Checklist:

• My change requires a change to the documentation or CHANGELOG.
• I have updated the documentation/CHANGELOG accordingly.
• I have created a feature (non-master) branch for my PR.

[JoelSpeed]

Have you had a chance to manually test this?

We should make sure we have a test in place that checks for duplicates in the flag and cfg options 🤔

[NickMeves]

I think I should do more manual testing. I only spun one up with our contrib area with a metrics port enabled to recreate the reporter's original bug (I couldn't - they must have other flags intermixed giving that scenario where it is complaining about not starting up an HTTP non-secure metrics endpoint).

I'll find some time to get some local certs in place to test the secure version with this fix.