Fix EMotionFX Editor tests to compile with -Wshorten-64-to-32

Signed-off-by: Chris Burel <burelc@amazon.com>

Gems/EMotionFX/Code/Tests/UI/CanAddMotionToAnimGraphNode.cpp

@@ -49,7 +49,7 @@ namespace EMotionFX
         ASSERT_TRUE(motionSetWindow) << "No motion set window found";
 
         // Check there aren't any motion sets yet.
-        const AZ::u32 numMotionSets = EMotionFX::GetMotionManager().GetNumMotionSets();
+        const size_t numMotionSets = EMotionFX::GetMotionManager().GetNumMotionSets();
         EXPECT_EQ(numMotionSets, 0);
 
         // Find the action to create a new motion set and press it.
@@ -58,7 +58,7 @@ namespace EMotionFX
         QTest::mouseClick(addMotionSetButton, Qt::LeftButton);
 
         // Make sure the new motion set has  been created.
-        const AZ::u32 numMotionSetsAfterCreate = EMotionFX::GetMotionManager().GetNumMotionSets();
+        const size_t numMotionSetsAfterCreate = EMotionFX::GetMotionManager().GetNumMotionSets();
         ASSERT_EQ(numMotionSetsAfterCreate, numMotionSets + 1) << "Failed to create motion set.";
 
         EMotionFX::MotionSet* motionSet = EMotionFX::GetMotionManager().GetMotionSet(0);