Unregister custom SettingsRegistries in the test Teardown

Code/Tools/AssetProcessor/native/tests/platformconfiguration/platformconfigurationtests.cpp

@@ -49,7 +49,7 @@ void PlatformConfigurationUnitTests::SetUp()
         + "/project_path";
     registry->Set(projectPathKey, "AutomatedTesting");
     AZ::SettingsRegistryMergeUtils::MergeSettingsToRegistry_AddRuntimeFilePaths(*registry);
-    
+
     using namespace AssetProcessor;
     m_qApp = new QCoreApplication(m_argc, m_argv);
     AssetProcessorTest::SetUp();
@@ -61,6 +61,12 @@ void PlatformConfigurationUnitTests::TearDown()
     AssetUtilities::ResetAssetRoot();
     delete m_qApp;
     AssetProcessor::AssetProcessorTest::TearDown();
+
+    auto settingsRegistry = AZ::SettingsRegistry::Get();
+    if(settingsRegistry == &m_registry)
+    {
+        AZ::SettingsRegistry::Unregister(settingsRegistry);
+    }
 }
 
 TEST_F(PlatformConfigurationUnitTests, TestFailReadConfigFile_BadPlatform)