svn commit: r81756 - release/arrow/apache-arrow-adbc-21

[lidavidm]

Author: lidavidm
Date: Fri Jan  9 07:55:16 2026
New Revision: 81756

Log:
Remove old Apache Arrow ADBC release: apache-arrow-adbc-21/

Deleted:
   release/arrow/apache-arrow-adbc-21/