Vector load/store lane, splat, extend as well as load 32/64 zero
have been rewritten to make use of new z15 instructions (or use
older instructions if not available) in such Cls:
https://crrev.com/c/3138212
https://crrev.com/c/3144373

Same has been done for PPC BE (AIX).
As a result the workarounds in wasm-compiler are no longer needed.

Change-Id: I1de7066fa20f6e4d9d68c1a6db77a164dc8ae2f1
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3379820Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Milad Farazmand <mfarazma@redhat.com>
Cr-Commit-Position: refs/heads/main@{#78572}