Big Bang Bot: Update CODEOWNERS

Action	User	Reason
Remove	@jamie.causey	Employment dates no longer active
---------	---------	-----------
Error	@	Too few codeowners, minimum is: 3

This package is not currently tracked in the team charter mission team manifest. As such, only expired/unrecognized users have been removed. If you would like this package to sync with the manifest file, please refer to updating team charter manifest.