[wasm][cleanup] Make cctests in test-run-wasm.cc use page-sized memory

Bug: v8:7704, v8:7570
Change-Id: I671f1355b9a95b0fcba56ac5fb3669b4563652dc
Reviewed-on: https://chromium-review.googlesource.com/1033543
Commit-Queue: Eric Holk <eholk@chromium.org>
Reviewed-by: Deepti Gandluri <gdeepti@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52868}