databases/xtrabackup80: renamed from databases/xtrabackup8 and updated

The port databases/xtrabackup8 upgraded to version 8.0.35-30
and renamed to databases/xtrabackup80 in preparation for upcoming
incompatible branch databases/xtrabackup81, to avoid confusion.

Drop unused dependency on libncurses.

The update based on maintainer's submittion.

PR: 277088
Tested by: Eugene M. Zheganin (maintainer)
Approved by: Eugene M. Zheganin (maintainer)