Currently our builder images are built only in x86.

To be able to support multi-arch jobs in Prow, we need to have those images also available in other architectures.

We need then to update our Makefile in test-infra so that we build and push the builder image to quay for x86, s390x an powerpc platforms.

This article might be useful: https://www.docker.com/blog/multi-arch-build-and-images-the-simple-way/

A/C:

• We have (2.2), 2.3, 2.4 builder image pushed to Quay in all supported (x86,z,p) platforms.