[wasm-simd] Remove post-mvp flag from i64x2.all_true tests

Bug: v8:11347
Change-Id: I17859b226e14df63380dd6895bee62b0e8a380b9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2719297


Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Commit-Queue: Zhi An Ng <zhin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#73063}