Some cctests set the FLAG_stack_size in the TEST() macro which is run
after the cctest runner initializes the main isolate. The flag is only
used during isolate initialization, so this did not have any effect.

This fixes it by using the UNINITIALIZED_TEST() macro, creating the
isolate after setting the flag and passing it through to the WasmRunner.

See also https://crrev.com/c/2862778 which fixes JS cctests.

R=jkummerow@chromium.org

Change-Id: I46df22b80a283d93c48c1dbd250eb3e4ea5ad4a0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2865749
Commit-Queue: Thibaud Michaud <thibaudm@chromium.org>
Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Cr-Commit-Position: refs/heads/master@{#74331}