Use exclusions in CODEOWNERS

What does this MR do and why?

Use exclusions in CODEOWNERS

We previously used a quirk in the logic of CODEOWNERS to prevent some of the files from requiring approval due to the * entry on line 5.

CODEOWNERS currently sets any approval rules without any approvers to auto-approved.

We recently implemented an exclusion feature which would achieve the same result without needing to populate an approval rule and auto-approve it: https://docs.gitlab.com/user/project/codeowners/reference/#exclusion-patterns

Currently viewing the .gitlab/CODEOWNERS file we can see these entries return Zero owners errors.

Viewing the file after this change reveals more errors. Currently the CODEOWNERS validation logic will only move onto querying the database if no syntax errors were found. We can see that there are actually 360 owners without permission to merge which are currently not visible due to the syntax errors.