The test started failing on win64 ASan after a DEPS roll. Increase the
stack size to mitigate this.
Also, add a comment so say why we are restricting the stack size in the
first place.

R=thibaudm@chromium.org
CC=ahaas@chromium.org

Bug: v8:11120
Cq-Include-Trybots: luci.v8.try:v8_win64_asan_rel_ng
Change-Id: If0c084653687aef95acee8caa6712a1c872d2bca
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2523203Reviewed-by: Thibaud Michaud <thibaudm@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#71016}