Fix Assert Absorber being leaked due to one of the tests setting m_errorAbsorber to nullptr without deleting the object (#5176) (#5348)

Signed-off-by: amzn-mike <80125227+amzn-mike@users.noreply.github.com>
(cherry picked from commit 916fb413c9)

Code/Tools/AssetProcessor/native/tests/AssetProcessorTest.h

@@ -25,7 +25,7 @@ namespace AssetProcessor
         : public ::testing::Test
     {
     protected:
-        UnitTestUtils::AssertAbsorber* m_errorAbsorber;
+        AZStd::unique_ptr<UnitTestUtils::AssertAbsorber> m_errorAbsorber{};
         FileStatePassthrough m_fileStateCache;
 
         void SetUp() override
@@ -40,7 +40,7 @@ namespace AssetProcessor
                 m_ownsSysAllocator = true;
                 AZ::AllocatorInstance<AZ::SystemAllocator>::Create();
             }
-            m_errorAbsorber = new UnitTestUtils::AssertAbsorber();
+            m_errorAbsorber = AZStd::make_unique<UnitTestUtils::AssertAbsorber>();
 
             m_application = AZStd::make_unique<AzFramework::Application>();
 
@@ -62,8 +62,8 @@ namespace AssetProcessor
             AssetUtilities::ResetAssetRoot();
             
             m_application.reset();
-            delete m_errorAbsorber;
-            m_errorAbsorber = nullptr;
+            m_errorAbsorber.reset();
+
             if (m_ownsSysAllocator)
             {
                 AZ::AllocatorInstance<AZ::SystemAllocator>::Destroy();