databases/pgbackrest: Update 2.58.0 => 2.59.1

Release Notes:
https://pgbackrest.org/release.html#2.59.1

Changelogs:
https://github.com/pgbackrest/pgbackrest/releases/tag/release/2.59.0
https://github.com/pgbackrest/pgbackrest/releases/tag/release/2.59.1

• Explicitly disable libsystemd (new upstream dependency) because the autodetection doesn't work.
• Switch to prepared by upstream tarball (new in 2.59.0).
• Remove unused textproc/libyaml from LIB_DEPENDS.
• Convert *_MESON_ON/OFF to *_MESON_ENABLED.

PR: 297665
Approved by: Michael Schout <schoutm@gmail.com>
Sponsored by: UNIS Labs
Co-authored-by: Brad Ackerman <brad@facefault.org>
MFH: 2026Q3