VPA: Add recommender Prometheus metrics tests

[mattsu2020]

What type of PR is this?

/kind feature

What this PR does / why we need it:

Adds unit coverage for the VPA recommender Prometheus RoundTripper metrics introduced for Prometheus history provider API requests.

The new test exercises the counter and duration wrappers with an HTTP response and verifies the expected code and method labels are recorded.

Fixes #8128

Which issue(s) this PR fixes:

Fixes #8128

Special notes for your reviewer:

NONE

Does this PR introduce a user-facing change?

NONE

Validation:

go test ./pkg/utils/metrics/recommender
go test ./pkg/recommender/input/history

[k8s-ci-robot]

This issue is currently awaiting triage.

If SIG Autoscaling contributors determines this is a relevant issue, they will accept it by applying the triage/accepted label and provide further guidance.

The triage/accepted label can be added by org members by writing /triage accepted in a comment.

Details

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-sigs/prow repository.

[k8s-ci-robot]

Welcome @mattsu2020!

It looks like this is your first PR to kubernetes/autoscaler 🎉. 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/autoscaler 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]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: mattsu2020
Once this PR has been reviewed and has the lgtm label, please assign omerap12 for approval. For more information see the Code Review Process.

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

Details

Needs approval from an approver in each of these files:

• vertical-pod-autoscaler/OWNERS

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

[k8s-ci-robot]

Hi @mattsu2020. 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.

Details

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-sigs/prow repository.

[adrianmoisey]

/remove-kind feature
/kind cleanup
/ok-to-test