{NativeModuleSerializer::WriteCode} does always return {true}, hence
remove the return value to avoid dead code in callers.

R=ahaas@chromium.org

Bug: v8:12425
Change-Id: I3c07829f327fc039b3baffdec3f9f6637adc2861
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3425357Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78866}