[wasm][c-api] Avoid flag updates after initialization

There are two flag updates from the Wasm C-API. Both are unnecessary:
FLAG_expose_gc is not needed because we call the internal API for
garbage collection; this is always allowed.
FLAG_experimental_wasm_eh is enabled by default, so does not need to be
set to true in that test.

R=jkummerow@chromium.org

Bug: v8:12887
Change-Id: If56506228cd89d5452e71376e4c2f6a4ec636979
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3687690Reviewed-by: Jakob Kummerow <jkummerow@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#80939}

src/wasm/c-api.cc

@@ -399,9 +399,6 @@ auto Engine::make(own<Config>&& config) -> own<Engine> {
   }
 #endif
   v8::V8::Initialize();
-  // The commandline flags get loaded in V8::Initialize(), so we can override
-  // the flag values only afterwards.
-  i::FLAG_expose_gc = true;
   return make_own(seal<Engine>(engine));
 }
 

test/wasm-api-tests/traps.cc

@@ -35,7 +35,6 @@ void ExpectMessage(const char* expected, const Message& message) {
 }  // namespace
 
 TEST_F(WasmCapiTest, Traps) {
-  FLAG_experimental_wasm_eh = true;
   ValueType i32_type[] = {kWasmI32};
   FunctionSig sig(1, 0, i32_type);
   uint32_t callback_index =