tests: Use Gentoo binary packages #955

Job	Run time
OS (apt-docker.io/amd64/ubuntu:devel)	1m 55s
OS (apt-docker.io/amd64/ubuntu:latest)	2m 9s
OS (apt-docker.io/amd64/ubuntu:rolling)	1m 46s
OS (apt-docker.io/i386/debian:testing)	1m 47s
OS (apt-docker.io/amd64/debian:testing)	1m 56s
OS (dnf-registry.fedoraproject.org/fedora:latest)	2m 36s
OS (dnf-registry.fedoraproject.org/fedora:rawhide)	2m 30s
OS (alpine-docker.io/alpine)	33s
OS (alpine-docker.io/i386/alpine)	32s
OS ([email protected]/alpine)	34s
OS (nix-docker.io/nixos/nix)	1m 2s
OS (gentoo-)	3m 50s
OS (alpine@gudev-alpine, EXTRA_PACKAGES=libgudev-dev)	33s
	21m 43s

Provide feedback