Remove empty Management folder and add metadata for M365 workflows

- Removed empty Management folder that was not being used
- Added metadata.yaml for workflows/community/M365/ to maintain consistency with other workflow folders
- Metadata describes M365 user and mailbox security management workflows

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: nate-smalls-s1