Keep only x86-64/aarch64 qemu-user-static packages

The containers-common package pulls in all qemu-user-static packages as a recommends but it's unlikely that users will need to run binaries from very uncommon architectures on their x86_64/aarch64 systems.

Thus we should only keep:

• the x86 qemu-user-static one on aarch64/ppc64le as this is more likely the main use case for running x86-64 containers on those architectures.
• the aarch64 qemu-user-static one on x86-64 as this is also the one most likely to be used for testing containers for aarch64.

All the other architectures can be installed via layering or maybe via a sysext in the future.

See other discussions:

• https://github.com/coreos/fedora-coreos-tracker/issues/1088
• https://github.com/coreos/fedora-coreos-tracker/issues/1237