Remove unused contribution files for Docs- Runner

What does this MR do?

With the Merge Request in place: Derive localized /development pages from English sources, we've now successfully removed the dependency on having any of the /development or contribution files in the /doc-locale directory. Removing the complete directory from the /ja-jp side. There's currently no other /development files in /fr-fr or /ko-kr , so we can safely ignore these two directories.

Here's the list of all of the relevant MRs:

1. GitLab: Remove unused contribution files for Docs - GitLab (gitlab!249035 - merged)
2. Charts: Remove unused contribution files for Docs - Charts (gitlab-org/charts/gitlab!5252 - merged)
3. Runner: Remove unused contribution files for Docs- Runner (!7143 - merged)
4. Omnibus: Remove unused contribution files for Docs - Omn... (omnibus-gitlab!9655 - merged)
5. Operator: Remove unused contribution files for Docs - Ope... (gitlab-org/cloud-native/gitlab-operator!1603 - merged)

Why was this MR needed?

The docs site intentionally doesn't translate the Contribute (/development/) docs. Originally, we decided to copy all the development content with only front-matter intact for Japanese under this issue: MVC to hide "Contribute" pages and navigation in Japanese localized docs site. However, the with time, a lot of these development pages are constantly moved, deleted or more pages are created, so this initial MVC doesn't work anymore.

What's the best way to test this MR?

Essentially we can follow the exact same steps derived here: gitlab-org/technical-writing/docs-gitlab-com!2501 (merged), but specifically focus only on the /development files located under https://docs.gitlab.com/runner/development/ as they are strictly related to runner project.

What are the relevant issue numbers?

gitlab-com/localization/docs-site-localization#998 (closed)