databases/mysql97-{client,server}: Update to 9.7.2

This release contains the security fixes of the Oracle Critical
Patch Update of July 2026. 43 of the 54 MySQL issues apply to the
9.7 series and to the MySQL Router built from this port.

Drop patch-libs_mysql_gtid_tag__plain.h, the type_traits include
is upstream as of 9.7.2.

Changes:
https://dev.mysql.com/doc/relnotes/mysql/9.7/en/news-9-7-2.html

Security: 10f5f76e-90a5-11f1-bc30-3497f65b111b
Sponsored by: Netzkommune GmbH