Skip heavy CI for documentation-only and comment-only changes

[yankay]

What would you like to be added

For PRs that only change documentation files (docs/**, *.md, OWNERS, etc.), skip the heavy CI pipelines (KubeVirt deploy, molecule, vagrant tests) and only run lightweight checks like linting.

Why is this needed

Currently every PR triggers the full CI regardless of what files changed. A simple markdown typo fix has to wait for full cluster deployments, wasting CI resources and slowing down doc contributors.

Reference: kubernetes-sigs/cluster-api#8151 implemented the same optimization.

/kind feature

[VannTen]

This isn't possible with the current setup (failfast-ci integrating github with gitlab-ci, changed files are not preserved).
We'll revisit if/when we migrate to Prow ( see #10682 )