Remove files that exist at the top level too

Workhorse does not need its own license or contributing
guidelines. Whatever applies to gitlab-org/gitlab applies
to gitlab-org/gitlab/workhorse too.

workhorse/CONTRIBUTING.md

-## Contributing
-
-Thank you for your interest in contributing to this GitLab project! We welcome
-all contributions. By participating in this project, you agree to abide by the
-[code of conduct](#code-of-conduct).
-
-## Contributor license agreement
-
-By submitting code as an individual you agree to the [individual contributor
-license agreement][individual-agreement].
-
-By submitting code as an entity you agree to the [corporate contributor license
-agreement][corporate-agreement].
-
-## Code of conduct
-
-As contributors and maintainers of this project, we pledge to respect all people
-who contribute through reporting issues, posting feature requests, updating
-documentation, submitting pull requests or patches, and other activities.
-
-We are committed to making participation in this project a harassment-free
-experience for everyone, regardless of level of experience, gender, gender
-identity and expression, sexual orientation, disability, personal appearance,
-body size, race, ethnicity, age, or religion.
-
-Examples of unacceptable behavior by participants include the use of sexual
-language or imagery, derogatory comments or personal attacks, trolling, public
-or private harassment, insults, or other unprofessional conduct.
-
-Project maintainers have the right and responsibility to remove, edit, or reject
-comments, commits, code, wiki edits, issues, and other contributions that are
-not aligned to this Code of Conduct. Project maintainers who do not follow the
-Code of Conduct may be removed from the project team.
-
-This code of conduct applies both within project spaces and in public spaces
-when an individual is representing the project or its community.
-
-Instances of abusive, harassing, or otherwise unacceptable behavior can be
-reported by emailing contact@gitlab.com.
-
-This Code of Conduct is adapted from the [Contributor Covenant][contributor-covenant], version 1.1.0,
-available at [http://contributor-covenant.org/version/1/1/0/](http://contributor-covenant.org/version/1/1/0/).
-
-[contributor-covenant]: http://contributor-covenant.org
-[individual-agreement]: https://docs.gitlab.com/ee/legal/individual_contributor_license_agreement.html
-[corporate-agreement]: https://docs.gitlab.com/ee/legal/corporate_contributor_license_agreement.html

workhorse/LICENSE

-The MIT License (MIT)
-
-Copyright (c) 2015-2017 GitLab B.V.
-
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
-
-The above copyright notice and this permission notice shall be included in
-all copies or substantial portions of the Software.
-
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
-THE SOFTWARE.