chore: remove invalid CODOWNERS file (#855)

* chore: remove invalid CODOWNERS file

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

* update generatedFiles list to exclude CODEOWNERS

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

synth.metadata

@@ -16,7 +16,6 @@
     }
   ],
   "generatedFiles": [
-    ".github/CODEOWNERS",
     ".github/ISSUE_TEMPLATE/bug_report.md",
     ".github/ISSUE_TEMPLATE/feature_request.md",
     ".github/ISSUE_TEMPLATE/support_request.md",