Add R&D specialty to team drop down and clean up data

The MR introduces a manually run script to clean up duplicate entries in departments when looking at division, team tags, and (for Engineering and Product) specialty; and the changes as a result of the script being run.

The MR also adds specialty for Engineering and Product in the team page drop down to reduce duplication in departments, and updates the relevant readme with the updated information.

Handbook MR: gitlab-com/content-sites/docsy-gitlab!238 (merged)