net-mgmt/cacti-spine: Update 1.2.28 => 1.2.29

Along with updating net-mgmt/cacti also net-mgmt/cacti-spine could be
updated.

Changelog:
http://www.cacti.net/info/changelog

Improve port:

• replace PORTVERSION with DISTVERSION,
• remove GNU_CONFIGURE_MANPREFIX,
• pet portclippy - move USES higher,
• sort USES,
• split long lines.

PR: 284586
Approved by: skreuzer (maintainer, timeout > 2 weeks)
MFH: 2025Q1