tests: Fix meson log printing in run-nix #990

Job	Run time
OS (apt-docker.io/amd64/ubuntu:devel)	1m 51s
OS (apt-docker.io/amd64/ubuntu:latest)	1m 59s
OS (apt-docker.io/amd64/ubuntu:rolling)	1m 47s
OS (apt-docker.io/i386/debian:testing)	1m 44s
OS (apt-docker.io/amd64/debian:testing)	1m 57s
OS (dnf-registry.fedoraproject.org/fedora:latest)	2m 45s
OS (dnf-registry.fedoraproject.org/fedora:rawhide)	6m 51s
OS (alpine-docker.io/alpine)	27s
OS (alpine-docker.io/i386/alpine)	44s
OS ([email protected]/alpine)	31s
OS (nix-docker.io/nixos/nix)	55s
OS (gentoo-)	5m 23s
OS (alpine@gudev-alpine, EXTRA_PACKAGES=libgudev-dev)	32s
	27m 26s

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