Don't use portsnap anymore to manage FreeBSD ports

Summary:
Portsnap is deprecated, and, as such, has been removed from the base system
in FreeBSD 14. This change takes care of removing portsnap installation,
use and periodic configuration.

This reverts commit 0925ab320bd2ae3ddd6581fc71681aed5dc7d210.
This reverts commit c6ea8cdd4d8f9c6077b225c607e19832abf85402.
This reverts commit 465b1adbe14724e1f865da5f3e636289032e7ed7.
This reverts commit a076e369fe1ce6e1f8decf644781ec1ad0bfb6fb.

Ref T2019.

Reviewers: dereckson, DorianWinty

Reviewed By: DorianWinty

Maniphest Tasks: T2019

Differential Revision: https://devcentral.nasqueron.org/D3443