Setup workflow testing for external contributor

[Boomatang]

What

There is a PR from an external contributor that has failing e2e tests.
As they are not part of the org they do not have the correct permissions to run the tests.

This is expected, drive by PRs should not trigger the CI/CD for the costly e2e tests.
But currently there is no way to trigger those tests manually with the correct permissions.

Examples

• https://github.com/Kuadrant/dns-operator/actions/runs/22343955042/job/64653669828?pr=745

Done

• There is a way for org members to allow the full workflow to run on external contributors PR's.