CODEOWNERS fails to notify on failure to sync

### Problem Statement

Hey, we use CODEOWNERS integration with teams mapping and auto-assigning. It is very easy to miss syncing issues: some time ago, we made some group changes, and syncing stopped working because of missing mapping rules. We discovered that accidentally after 3 months (!). During this period, developers pushed new CODEOWNERS changes and did not understand why they sometimes did not work correctly

### Solution Brainstorm

Having simple notifications, alerts, and status info about CODEOWNERS syncing will be nice: by slack or just via email. Then, proper persons can quickly fix missing mappings or CODEOWNERS file format

### Product Area

Settings - Repositories

The issue does not name files, tests, or entry points. Start by locating the CODEOWNERS integration sync flow, teams mapping rules, and repository Settings area; clarify whether the intended outcome is Slack or email notifications, status information, or both, and define the failure cases that must be reported.

Written by the indexing model from the issue text.