Load extends always load 8 bytes, so the access size does not depend on
MachineType of the load. The MachineType is used for classifying the
lane shape of the 8-byte load.

Also add cctest to load splats and load extends to test OOB. (Note that
load splats access size depends on MachineType).

Add regression test from clusterfuzz, minimized by ahaas@. Remove the
`--no-wasm-trap-handler` flag since we have a no_wasm_traps variant that
should test this flag.

Bug: chromium:1116019
Change-Id: I27ba051d0536ca0f6fd75dd641ca9b78132dafed
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2363291
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69489}