Add opentracing operation name settings

[bvandewalle]

What this PR does / why we need it:

Based on stale PR #4118
In order to set custom span names for server and location span use the following config items in the configmap:

opentracing-operation-name: "HTTP $request_method $uri"
opentracing-location-operation-name: "HTTP $request_method $uri"

Which issue/s this PR fixes

fixes #5829
fixes #4116

How Has This Been Tested?

Original PR had some E2E tests. Modified them to make them load a tracer (Zipkin in this case, this is required for nginx to not crash)

Checklist:

• [ x] My change requires a change to the documentation.
• [ x] I have updated the documentation accordingly.
• [ x] I've read the CONTRIBUTION guide
• [ x] I have added tests to cover my changes.
• [ x] All new and existing tests passed.

[k8s-ci-robot]

Welcome @bvandewalle!

It looks like this is your first PR to kubernetes/ingress-nginx 🎉. Please refer to our pull request process documentation to help your PR have a smooth ride to approval.

You will be prompted by a bot to use commands during the review process. Do not be afraid to follow the prompts! It is okay to experiment. Here is the bot commands documentation.

You can also check if kubernetes/ingress-nginx has its own contribution guidelines.

You may want to refer to our testing guide if you run into trouble with your tests not passing.

If you are having difficulty getting your pull request seen, please follow the recommended escalation practices. Also, for tips and tricks in the contribution process you may want to read the Kubernetes contributor cheat sheet. We want to make sure your contribution gets all the attention it needs!

Thank you, and welcome to Kubernetes. 😃

[k8s-ci-robot]

Hi @bvandewalle. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[bvandewalle]

@JorritSalverda In case you are still following this, it's based on your PR. Thanks for the initial work.

[aledbf]

/ok-to-test

[bvandewalle]

/retest

[aledbf]

/retest

[aledbf]

/lgtm
/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: aledbf, bvandewalle

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [aledbf]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[aledbf]

@bvandewalle thanks!