ports-mgmt/pkg_rmleaves: Update 20231217 => 20260412

Changelog:

• Show at most 250 leaf packages at a time (over multiple dialogs if needed) to stay within ARG_MAX kernel limit for command line arguments to bsddialog.
• Support for the very old FreeBSD pkg_delete package manager is now deprecated and will be removed completely in next release.

Port changes:

• Pet portfmt: add newline PLIST_FILES.
• Switch to PORTVERSION.

PR: 294435
See also: 294368
Reported by: Alexander Wittig <alexander@wittig.name> (maintainer)
Reported by: Cy Schubert <cy@FreeBSD.org>
Approved by: osa, vvd (mentors)
MFH: 2026Q2

(cherry picked from commit df9cfd6f5132787b358b24b5d68a77b3061d29ec)