tests: remove legacy test tree

tests/threading/test_mutex.cpp

@@ -1,41 +0,0 @@
-#include <gtest/gtest.h>
-#include <XCEngine/Threading/Mutex.h>
-
-using namespace XCEngine::Threading;
-
-namespace {
-
-TEST(Threading_Mutex, LockUnlock) {
-    Mutex mutex;
-    
-    mutex.Lock();
-    mutex.Unlock();
-}
-
-TEST(Threading_Mutex, TryLock_Success) {
-    Mutex mutex;
-    
-    bool result = mutex.TryLock();
-    EXPECT_TRUE(result);
-    mutex.Unlock();
-}
-
-TEST(Threading_Mutex, TryLock_AlreadyLocked) {
-    Mutex mutex;
-    
-    mutex.Lock();
-    bool result = mutex.TryLock();
-    EXPECT_FALSE(result);
-    mutex.Unlock();
-}
-
-TEST(Threading_Mutex, MultipleLockUnlock) {
-    Mutex mutex;
-    
-    for (int i = 0; i < 10; ++i) {
-        mutex.Lock();
-        mutex.Unlock();
-    }
-}
-
-} // namespace