chore(repo): clear CODEOWNERS entries (#2201)

Remove all ownership rules from CODEOWNERS while keeping the file in
the repo. The previous entries assigned review ownership for i18n files
to @mattermost/playbooks and @ghost which is no longer needed.

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: calebroseland

CODEOWNERS

@@ -1,6 +1 @@
 
-# i18n PRs
-webapp/i18n/* @mattermost/playbooks
-webapp/i18n/en.json @ghost
-assets/i18n/* @mattermost/playbooks
-assets/i18n/en.json @ghost