Setting MSteams card summary to alert title

[dfitton]

Very small adjustment to the msteams alert plugin. Add "summary" line to replace 'Sent a Card' In Teams message preview with title of the alert.

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[dfitton]

I have read the CLA Document and I hereby sign the CLA or my organization already has a signed CLA.

[mathieu-sobrero]

Hi @dfitton

Thank you for contributing to Checkmk.
After reviewing the PR, we decided to do not integrate your commit as the PR affects the deprecated webhooks.
According to Microsoft, the webhooks are already deprecated and set to be completely removed by the end of 2025:
https://devblogs.microsoft.com/microsoft365dev/retirement-of-office-365-connectors-within-microsoft-teams/

If you wish to update your PR to work with Workflows, we would be happy to review it again.

Thank you.