go: Stop thinning testdata
go: Stop thinning testdata

It looks like we only are because the test harness code was based
on that for rust, which was based on that for javascript, which
was only thinning because it was reading everything into memory
and the larger vocabulary lists were resulting in out of memory
issues.

snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball,snowballstem/snowball