feat: SITES-39444 Autofix Slack trigger

[rmanolescu-adobe]

Please ensure your pull request adheres to the following guidelines:

• make sure to link the related issues in this description
• when merging / squashing, make sure the fixed issue references are visible in the commits, for easy compilation of release notes
• If data sources for any opportunity has been updated/added, please update the wiki for same opportunity.

Related Issues

SITES-39444- Autofix Slack trigger

Changes

• Simplified sendMystiqueMessage function (removed code fix flow complexity)
• Renamed aggregateA11yIssuesByOppType to aggregateAccessibilityIssues
• Updated suggestion key building logic
• Cleaned up unused exports and imports

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.

📢 Thoughts on this report? Let us know!