Re-add preemption victims metric as histogram

[arapulido]

What does this PR do?

Re-adds pod_preemption_victims metric as a histogram

Motivation

The pod_preemption_victims metric had a couple of changes over time that were not reflected in the integration.

First, in 1.17, it was moved from a Gauge to a Histogram.

Then, in 1.19 it changed its name to preemption_victims.

These changes were not reflected in the integration, and the metric was lost.

This PR readds that metrics back (with the new name, as a histogram).

Review checklist (to be filled by reviewers)

• Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
• PR title must be written as a CHANGELOG entry (see why)
• Files changes must correspond to the primary purpose of the PR as described in the title (small unrelated changes should have their own PR)
• PR must have changelog/ and integration/ labels attached

[codecov]

Codecov Report

Merging #12659 (c3fcd31) into master (dea6c14) will increase coverage by 0.00%.
The diff coverage is 100.00%.

Flag	Coverage Δ
kube_scheduler	97.05% <100.00%> (+0.05%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[ahmed-mez]

I think https://github.com/DataDog/integrations-core/blob/master/kube_scheduler/metadata.csv should be updated accordingly, kube_scheduler.pod_preemption.victims is marked as gauge.

[arapulido]

@ahmed-mez done

[github-actions]

The validations job has failed; please review the Files changed tab for possible suggestions to resolve.

[FlorentClarret]

👍