MON-3900: follow-up: clean up operator logic and some tests now that metrics-server is the default Metrics API backend

[machine424]

Came across this while working on https://github.com/openshift/cluster-monitoring-operator/pull/2423

/cc @slashpai @jan--f

/hold let's wait for https://github.com/openshift/cluster-monitoring-operator/pull/2423 to get merged first.

• [ ] I added CHANGELOG entry for this change.
• [ ] No user facing changes, so no entry in CHANGELOG was needed.

[openshift-ci-robot]

@machine424: This pull request references MON-3900 which is a valid jira issue.

Warning: The referenced jira issue has an invalid target version for the target branch this PR targets: expected the story to target the "4.17.0" version, but no target version was set.

In response to [this](https://github.com/openshift/cluster-monitoring-operator/pull/2425): >Came across this while working on https://github.com/openshift/cluster-monitoring-operator/pull/2423 > >/cc @slashpai @jan--f > >/hold >let's wait for https://github.com/openshift/cluster-monitoring-operator/pull/2423 to get merged first. > > > >* [ ] I added CHANGELOG entry for this change. >* [ ] No user facing changes, so no entry in CHANGELOG was needed. > Instructions for interacting with me using PR comments are available [here](https://prow.ci.openshift.org/command-help?repo=openshift%2Fcluster-monitoring-operator). If you have questions or suggestions related to my behavior, please file an issue against the [openshift-eng/jira-lifecycle-plugin](https://github.com/openshift-eng/jira-lifecycle-plugin/issues/new) repository.

[slashpai]

Thank you. I was going to have this as follow up PR. We should be able to remove feature gate as well from api

[machine424]

/retest

[danielmellado]

/lgtm

[machine424]

/hold cancel

[jan--f]

Thanks! /lgtm

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: danielmellado, jan--f, machine424

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Needs approval from an approver in each of these files: - ~~[OWNERS](https://github.com/openshift/cluster-monitoring-operator/blob/master/OWNERS)~~ [danielmellado,jan--f,machine424] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment

[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD e94353eb920f812fe5b7de59e3d085ab3977b155 and 2 for PR HEAD f51127a05408271a18c328e68f2b15239e22971d in total

[openshift-ci-robot]

/retest-required

Remaining retests: 0 against base HEAD dc82562b94b2b9c36f908b3847ebede50c46f83e and 1 for PR HEAD f51127a05408271a18c328e68f2b15239e22971d in total

[openshift-ci[bot]]

@machine424: The following test failed, say /retest to rerun all failed tests or /retest-required to rerun all mandatory failed tests:

Test name	Commit	Details	Required	Rerun command
ci/prow/versions	f51127a05408271a18c328e68f2b15239e22971d	link	false	/test versions

Full PR test history. Your PR dashboard.

Instructions for interacting with me using PR comments are available [here](https://git.k8s.io/community/contributors/guide/pull-requests.md). If you have questions or suggestions related to my behavior, please file an issue against the [kubernetes-sigs/prow](https://github.com/kubernetes-sigs/prow/issues/new?title=Prow%20issue:) repository. I understand the commands that are listed [here](https://go.k8s.io/bot-commands).

[openshift-bot]

[ART PR BUILD NOTIFIER]

Distgit: cluster-monitoring-operator This PR has been included in build cluster-monitoring-operator-container-v4.17.0-202408020314.p0.g491ab3b.assembly.stream.el9. All builds following this will include this PR.