k8s-provider: Remove KUBEVIRT_CPU_MANAGER_POLICY

[lyarwood]

What this PR does / why we need it:

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
Fixes #

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• Upgrade: Impact of this change on upgrade flows was considered and addressed if required
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• Community: Announcement to kubevirt-dev was considered

Release note:

TBD

[kubevirt-bot]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[kubevirt-bot]

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[kubevirt-bot]

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

Test name	Commit	Details	Required	Rerun command
check-gocli	fb2a713	link	true	/test check-gocli
check-provision-k8s-1.29	fb2a713	link	true	/test check-provision-k8s-1.29
check-provision-k8s-1.31-s390x	fb2a713	link	true	/test check-provision-k8s-1.31-s390x

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