In `.gitlab-ci.yml`, rauc-bundle build and publish jobs all extends
`workspace-rules`, and the latter job needs the former job. This is
good.

However, with the rules defined on the upstream job
'.publish-rauc-bundle-to-hawkbit', gitlab always try to add rauc-bundle publish
jobs into pipeline, when the build jobs are not added, error occurs.

Signed-off-by: Chase Qi <chase.qi@linaro.org>