maintain: remove some unused server options

[dnephin]

This PR removes some unused loadCertificate logic and options from the server. We may restore this in the future when it is being used. For now I think it's better to remove it so that contributors are not distracted by it. Removing it also avoids doing unnecessary work on server startup.

This PR also moves one test file into the pki package. It was only testing things in that package. The pki package is also not used, but at least it's well contained and is not called by any production code.

[BruceMacD]

Any way we can capture this commit in an issue for loading certificates in Infra? It seems like an option we will want soon and I'd like an easy way to find this existing work.

[ssoroka]

It wasn't too long ago that I resolved the issue that asked for the ability to load user-specified certs. Seems like a step backwards. edit: misunderstood the issue

[dnephin]

Good call to create an issue about this. I was thinking of adding support for that next. I've created #2176 to track it.

I'm not really sure how this code being removed relates to users being able to specify their own cert and key. Supporting that should be really simple, just creating a tls.Config out of the config they provided. As far as I can tell, the code being removed does not actually allow a user to specify their own certificate. The certs are never referenced by the tls.Config we pass to the HTTP server.

I suspect we won't use any of what is being removed here to support #2176.

[ssoroka]

Ah, sorry, this is the certificate provider stuff. This is related to the plan that we will manage certificate rotation for the user. Can't say I'm excited to see it go away.

[dnephin]

Git makes it easy to restore it later. Is there an issue related to that feature? I can put a note into that issue to link back to this PR, so we can find it easily.

[ssoroka]

Relevant issues is #593

[ssoroka]

to explain more, this is part of the server-managed certificates, which is work-in-progress, and I think we still want to build and use it. Jeff put this on hold a couple months ago, so I'm not sure what the status is, but I don't think the code should be considered dead unless that feature is killed.

[CLAassistant]

All committers have signed the CLA.

[ssoroka]

discussed concerns. good to go.

[dnephin]

Thank you!