Install DNF package findutils in builder images

[Sopka]

The Gradle wrapper scripts necessitate the installation of the 'xargs' command. This command is supplied by the supplementary 'findutils' package.

[ThoSap]

I always added the findutils package to my custom Dockerfile.multistage-native Dockerfile so Gradle works.
This is a welcome change, as I no longer need to do that, thanks!

RUN microdnf install -y --setopt=install_weak_deps=0 findutils \
 && microdnf clean all -y \
 && [ ! -d /var/cache/yum ] || rm -rf /var/cache/yum

[cescoffier]

Thanks!