Update postmortem metadata constants for V8 7.8 in Node.js.

Change-Id: Ia2bf5ef611f4f6d87783b1fd1b340ae42e4a92a0
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1849139
Commit-Queue: Yang Guo <yangguo@chromium.org>
Reviewed-by: Yang Guo <yangguo@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64238}