[wasm][test] Remove check for use count of shared_ptr

The shared engine tests started flaking. They are broken since some
time, because the shared pointer to the {NativeModule} has temporary
additional users during compilation (in the {BackgroundCompileScope}).
This CL fixes the test by just removing the checks for use counts.

R=mstarzinger@chromium.org

Bug: v8:9117
Change-Id: Ia55ce66426f8d85c0ed8e4185aa6e507a6d327ef
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1564056
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Auto-Submit: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Michael Starzinger <mstarzinger@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60781}

test/cctest/wasm/test-wasm-shared-engine.cc

@@ -246,17 +246,13 @@ TEST(SharedEngineRunImported) {
     Handle<WasmInstanceObject> instance = isolate.CompileAndInstantiate(buffer);
     module = isolate.ExportInstance(instance);
     CHECK_EQ(23, isolate.Run(instance));
-    CHECK_EQ(2, module.use_count());
   }
-  CHECK_EQ(1, module.use_count());
   {
     SharedEngineIsolate isolate(&engine);
     HandleScope scope(isolate.isolate());
     Handle<WasmInstanceObject> instance = isolate.ImportInstance(module);
     CHECK_EQ(23, isolate.Run(instance));
-    CHECK_EQ(2, module.use_count());
   }
-  CHECK_EQ(1, module.use_count());
 }
 
 TEST(SharedEngineRunThreadedBuildingSync) {