treewide: update nic.cz gitlab-related links

.gitmodules

README.rst

ci/respdiff-run.sh

contrib/docker/README.rst

contrib/docker/knot-resolver-buildenv/Dockerfile

contrib/docker/knot-resolver-fedora/Dockerfile

contrib/docker/knot-resolver/Dockerfile

contrib/docker/resperf/Dockerfile

contrib/job_manager/files/docker-compose.yaml.j2

contrib/job_manager/files/run_distrotest.sh.j2

contrib/job_manager/files/run_respdiff.sh.j2

contrib/job_manager/files/run_resperf.sh.j2

...job_manager/test_cases/shortlist.fwd-tls6-kresd.udp6.yaml

...job_manager/test_cases/shortlist.fwd-udp6-kresd.udp6.yaml

...b_manager/test_cases/shortlist.fwd-udp6-unbound.tcp6.yaml

...b_manager/test_cases/shortlist.fwd-udp6-unbound.tls6.yaml

...b_manager/test_cases/shortlist.fwd-udp6-unbound.udp6.yaml

contrib/job_manager/test_cases/shortlist.iter.tls6.yaml

contrib/job_manager/test_cases/shortlist.iter.udp6.yaml

contrib/job_manager/test_cases/top10k.iter.tls.j128.yaml