[K/N] Move ClearCurrentThreadData() out of TestSupport

kotlin-native/runtime/src/mm/cpp/TestSupport.cpp

@@ -57,7 +57,7 @@ extern "C" void Kotlin_TestSupport_AssertClearGlobalState() {
 
 void kotlin::DeinitMemoryForTests(MemoryState* memoryState) {
     DeinitMemory(memoryState, false);
-    mm::ThreadRegistry::TestSupport::ClearCurrentThreadData();
+    mm::ThreadRegistry::ClearCurrentThreadData();
 }
 
 std::ostream& kotlin::operator<<(std::ostream& stream, ThreadState state) {

kotlin-native/runtime/src/mm/cpp/ThreadRegistry.hpp

@@ -43,10 +43,7 @@ public:
 
     bool IsCurrentThreadRegistered() const noexcept { return currentThreadDataNode_ != nullptr; }
 
-    class TestSupport {
-    public:
-        static void ClearCurrentThreadData() { currentThreadDataNode_ = nullptr; }
-    };
+    static void ClearCurrentThreadData() { currentThreadDataNode_ = nullptr; }
 
 private:
     friend class GlobalData;