🌱 Use org-wide workflows from .github repo (#16)

Remove duplicate caller workflows now provided org-wide from kubestellar/.github:
- add-help-wanted.yml, assignment-helper.yml, feedback.yml, greetings.yml
- pr-verifier.yml, pr-verify-title.yml, scorecard.yml

Signed-off-by: Andrew Anderson <andy@clubanderson.com>
Co-authored-by: Claude Opus 4.5 <noreply@anthropic.com>

Author: clubanderson