[turboshaft] Maglev-to-ts: fix debug-only leak of Parameter names

Bug: chromium:42204525
Change-Id: I3ae60b1a730a904bc23faab784a7dc8fe360bfb8
Fixed: chromium:350770683
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5713609


Auto-Submit: Darius Mercadier <dmercadier@chromium.org>
Commit-Queue: Darius Mercadier <dmercadier@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Cr-Commit-Position: refs/heads/main@{#95128}