Update to use AWSNativeSDK 1.9.50 (#6618)

* Update to use AWSNativeSDK 1.9.50
* After SDK upgrade, some AWS objects are bound to SDK allocator, init AWS SDK for unit test

Gems/AWSCore/Code/Tests/AWSCoreSystemComponentTest.cpp

@@ -19,6 +19,7 @@
 #include <AzTest/AzTest.h>
 
 #include <AWSCoreSystemComponent.h>
+#include <AWSNativeSDKInit/AWSNativeSDKInit.h>
 #include <Configuration/AWSCoreConfiguration.h>
 #include <Credential/AWSCredentialManager.h>
 #include <Framework/AWSApiJob.h>
@@ -103,6 +104,9 @@ public:
 
 TEST_F(AWSCoreSystemComponentTest, ComponentActivateTest)
 {
+    // Shutdown SDK which is init in fixture setup step
+    AWSNativeSDKInit::InitializationManager::Shutdown();
+
     EXPECT_FALSE(m_coreSystemsComponent->IsAWSApiInitialized());
 
     // activate component