ci-package-builder: Show final result in case of failure

To determine whether the build has been successful we check the code printed by osc result and grep for succeeded.

However, this means that if the result is not succeeded the pipeline gives no indication about what was the actual code.

To address that, show the full information from osc results and check it only later.

This MR is meant to shed some light on pipelines failing for unknown reasons like https://gitlab.apertis.org/pkg/target/prestwood/-/jobs/345583