Zombienet: add polkadot-debug image publish as needs for cumulus tests (#2493)

Add `build-push-image-polkadot-debug` job to needs since we changed to
use the polkadot-debug image from the current branch for cumulus test
and we need to be sure that the image is ready. Fix issues like
https://gitlab.parity.io/parity/mirrors/polkadot-sdk/-/jobs/4481059

cc: @bkchr



Co-authored-by: Bastian Köcher <[email protected]>