[heap] Fix marking state regression

Concurrent marking got accidentally disabled because
V8_ATOMIC_MARKING_STATE got removed.

Bug: v8:12470, chromium:1277264, chromium:1277330, chromium:1277392
Bug: chromium:1277287, chromium:1277260, chromium:1277259
Bug: chromium:1277256, chromium:1277252, chromium:1277250
Bug: chromium:1277254, chromium:1277251
Change-Id: I21211e8f6d3a65714ba3204e87863b71af42d82d
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3318663
Auto-Submit: Dominik Inführ <dinfuehr@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78269}

src/flags/flag-definitions.h

@@ -1251,7 +1251,7 @@ DEFINE_BOOL_READONLY(write_protect_code_memory, true,
 #else
 DEFINE_BOOL(write_protect_code_memory, true, "write protect code memory")
 #endif
-#if defined(V8_ATOMIC_MARKING_STATE) && defined(V8_ATOMIC_OBJECT_FIELD_WRITES)
+#if defined(V8_ATOMIC_OBJECT_FIELD_WRITES)
 #define V8_CONCURRENT_MARKING_BOOL true
 #else
 #define V8_CONCURRENT_MARKING_BOOL false