Do not include developmental dependencies in final licenses

From https://gitlab.com/gitlab-org/distribution/team-tasks/-/issues/874#note_635895068

omnibus-gitlab list of bundled licenses includes the licenses of gems used in development. These are omitted in GitLab's own license checks (see here), and should be omitted from the license list as well since these dependencies are not distributed with omnibus.

We need to confirm if this is the case, and fix omnibus (which use license_scout) or our usage of license_finder to correct this.