codeowners: remove cloud from shared files

Created by: keegancsmith

Cloud currently is the codeowner of many files that are modified by people all over Sourcegraph. As such our whole team is added to code reviews where our input really isn't required.

There is discussions about removing code owners entirely. This is a step in that direction for the more egregerious examples of it for cloud. If you thought it was important the reviewed you did on something I removed ownership on, please add your own name (instead of team) to the corresponding directory.