[wasm] Fix official build

Runtime::kWasmGenerateRandomModule only exists on non-official builds.

Change-Id: I7579d28247a27d895ce350ba012ea7b27623c3e7
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5724702


Auto-Submit: Matthias Liedtke <mliedtke@chromium.org>
Reviewed-by: Samuel Groß <saelo@chromium.org>
Commit-Queue: Samuel Groß <saelo@chromium.org>
Cr-Commit-Position: refs/heads/main@{#95151}