[wasm] Simplify LogCodesTask and fix race conditions

Based on the preceeding CL (https://crrev.com/c/5718231) we can greatly
simplify the LogCodesTask, relying on the CancellableTaskManager.
Instead of using a bunch of atomic values and pointers, we now update
all fields under the WasmEngine's mutex.

R=mliedtke@chromium.org

Bug: 42204620
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_dbg
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_isolates_rel
Cq-Include-Trybots: luci.v8.try:v8_linux64_tsan_rel
Change-Id: I13fabfbf3f388274030f72e36f7dad1b6b7b3d18
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/5718451


Reviewed-by: Matthias Liedtke <mliedtke@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#95135}