www/librewolf: Switch to use the builtin icu as devel/icu is too old on 2025Q1

PR: 285169
Reported by: cmt (via email)
Fixes: 189ac8337451 (Update 135.0.1 → 136.0)
MFH: 2025Q1

(cherry picked from commit 4288c5fbf380c14254082cb5326899f8406c3b37)