Drive-by fix to align what builds the test runner considers to be able
to have shared memory features and what builds can create a shared
Isolate.

Bug: v8:12007
Change-Id: I151513ccbfbee31e5b35c5ce8e9192732eabfee2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3421507Reviewed-by: Adam Klein <adamk@chromium.org>
Commit-Queue: Shu-yu Guo <syg@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78824}