NO-JIRA: tests(gha/k8s): remove setting the node-role.kubernetes.io/control-plane taint

[jiridanek]

Description

For some reason, the kubeadm.yaml was setting the taint only for build-notebooks-TEMPLATE.yaml to immediately unset it. This became obvious after migrating to v1beta4 kubeadm.yaml

How Has This Been Tested?

• https://github.com/jiridanek/notebooks/actions/runs/14928757209

Merge criteria:

• The commits are squashed in a cohesive manner and have meaningful messages.
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has manually tested the changes and verified that the changes work

[openshift-ci]

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[caponetto]

/lgtm