[wasm-gc] skip test on ppc/s390 platforms

Liftoff needs to be fully implemented for running this test.

Change-Id: Ia229d478fa22d4ce9a715d13b3d2b09a2634ad1c
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3163016


Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Milad Fa <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#76870}