NO-JIRA: pkg/helpers: remove legacy pkg

[flavianmissi]

we haven't supported "ungroupified" APIs for a couple of years. this cleans up the legacy package, effectively completely dropping support for them.

-- this is a follow up of https://github.com/openshift/oc/pull/1775.

[openshift-ci-robot]

@flavianmissi: This pull request explicitly references no jira issue.

In response to [this](https://github.com/openshift/oc/pull/1791): >we haven't supported "ungroupified" APIs for a couple of years. this cleans up the legacy package, effectively completely dropping support for them. > >-- >this is a follow up of https://github.com/openshift/oc/pull/1775. Instructions for interacting with me using PR comments are available [here](https://prow.ci.openshift.org/command-help?repo=openshift%2Foc). 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.

[flavianmissi]

/assign @ardaguclu

[ardaguclu]

This looks good to me. But before moving forward, it is better to wait the new nightly including the previous PR and check that everything is ok. After that, we can merge this.

[ardaguclu]

Thank you /lgtm /retest

[openshift-ci[bot]]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: ardaguclu, flavianmissi

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[openshift-ci[bot]]

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[openshift-bot]

[ART PR BUILD NOTIFIER]

This PR has been included in build openshift-enterprise-cli-container-v4.17.0-202406040742.p0.gb9859d5.assembly.stream.el9 for distgit openshift-enterprise-cli. All builds following this will include this PR.