[redcode/crythread-2nd-pass] replaced instances of AZStd::lock_guard<> with AZStd::scoped_lock as per feedback

Signed-off-by: AMZN-ScottR <24445312+AMZN-ScottR@users.noreply.github.com>

Code/Editor/CryEdit.cpp

@@ -938,10 +938,9 @@ void CCryEditApp::ShowSplashScreen(CCryEditApp* app)
 
     QObject::connect(splashScreen, &QObject::destroyed, splashScreen, [=]
     {
-        g_splashScreenStateLock.lock();
+        AZStd::scoped_lock lock(g_splashScreenStateLock);
         g_pInitializeUIInfo = nullptr;
         g_splashScreen = nullptr;
-        g_splashScreenStateLock.unlock();
     });
 }