Fix multiarch full image builds on PRs

[Molter73]

Description

There's a bug when building full multiarch images on PRs. The bucket used for pulling drivers is changed in the main CI workflow to use a staging bucket, but the main CI never pushes drivers for P/Z to this bucket, so it fails because it find no drivers to add into the image. Changing to the staging bucket should only be done by the CPaaS workflow, so an additional condition for this is added.

Checklist

• Investigated and inspected CI test results

Testing Performed

• Run CI with build-full-images, run-multiarch-builds and run-cpaas-steps. Ensure all used buckets are the expected ones.

[openshift-ci]

Skipping CI for Draft Pull Request.
If you want CI signal for your change, please convert it to an actual PR.
You can still manually trigger a test run with /test all

[github-actions]

Kernel	Method	Without Collector Time (secs)	With Collector Time (secs)	Baseline median (secs)	Collector median (secs)	PValue
ubuntu-os.ubuntu-2004-lts	ebpf	232.584	260.21	236.1	234.97	🟢