This CL fixes all spots where wasm Turbofan code did not satisfy the
invariant that all nodes with effect outputs are connected to another
node. Also, it enables the related verification for wasm code.

Drive-by:
- Simplify how stack checks are removed during loop unrolling.
- Fix a test declaration in test-gc.cc.

Change-Id: Id32af8584ba0ec281f4bf7757bd2915e6d8bf443
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3676862
Commit-Queue: Manos Koukoutos <manoskouk@chromium.org>
Reviewed-by: Tobias Tebbi <tebbi@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80854}