L::U is an arch-specific module (because it has a binary component), so the new version is probably installed in a directory that contains 5.24.1/x86_64-linux-64int in its path. The much older Perl you use via "your browser" won't look in that directory because it only contains modules it can't load.
You verify this using
use List::Util;
print $INC{"List/Util.pm"}, "\n";
That said, why are testing using one build of perl, and running using another? That makes no sense. Fix your shebang line, and your problem will be solved.
