chore: remove pr-verifier workflow

The gcr.io/kubebuilder/pr-verifier:v0.4.3 Docker image is no longer
available and the workflow has been breaking all PRs. Removing it entirely.

Signed-off-by: mjudeikis-bot <mjudeikis-bot@faros.sh>
Co-authored-by: Mangirdas Judeikis <mangirdas@judeikis.lt>

Author: mjudeikis-bot