Moving test back to xfail due to remaining issues with instance planting on meshes while null renderer is enabled

Signed-off-by: jckand-amzn <jckand@amazon.com>

AutomatedTesting/Gem/PythonTests/largeworlds/dyn_veg/test_PositionModifier.py

@@ -58,6 +58,7 @@ class TestPositionModifier(object):
     @pytest.mark.test_case_id("C4874100")
     @pytest.mark.SUITE_periodic
     @pytest.mark.dynveg_modifier
+    @pytest.mark.xfail      # LYN-3275
     def test_PositionModifier_AutoSnapToSurfaceWorks(self, request, editor, level, launcher_platform):
 
         expected_lines = [
@@ -74,6 +75,5 @@ class TestPositionModifier(object):
             editor,
             "PositionModifier_AutoSnapToSurfaceWorks.py",
             expected_lines,
-            cfg_args=[level],
-            null_renderer=False
+            cfg_args=[level]
         )