devel/subversion{,-lts}: remove port option STATIC

Since the switch to CMake for textproc/utf8proc
(207abfe1369d1ef1d89fae73b1091b37b9060ef7) the static library is not being built
anymore. This means that the static build of Subversion has been broken since
2022-01. For the past two years only one has complained (PR 279430) and
the maintainer of textproc/utf8proc (PR 280429) cannot easily provide an archive
with CMake anymore. Therefore, removing the STATIC port option for good.

PR: 279430
Approved by: jrm (mentor)
Differential Revision: https://reviews.freebsd.org/D46096