Manually upgrade GitLab UI _and_ GitLab SVGs

Unfortunately Renovate is currently mal-functioning, as we are hitting
this error: https://gitlab.com/gitlab-org/gitlab/-/issues/336657

Therefore we manually bump the GitLab UI version to the latest major.
This should have no impact on the GitLab project (apart from smaller
bundle size, due to new, aligned browser support), as all of the things
we need to migrate have been taken care of, _before_ we started merged
the new major release.