trim xfail cases

Author: jbrockmendel

pandas/tests/dtypes/cast/test_promote.py

@@ -334,14 +334,10 @@ def test_maybe_promote_any_with_datetime64(
 
     if boxed:
         if is_datetime64_dtype(dtype):
-            if box_dtype == object:
-                pytest.xfail("falsely upcasts to object")
-            elif box_dtype is None and not is_datetime64_dtype(type(fill_value)):
+            if box_dtype is None and not is_datetime64_dtype(type(fill_value)):
                 pytest.xfail("falsely upcasts to object")
         else:
-            if box_dtype == "dt_dtype":
-                pytest.xfail("mix of lack of upcasting, resp. wrong missing value")
-            elif box_dtype is None and is_datetime64_dtype(type(fill_value)):
+            if box_dtype is None and is_datetime64_dtype(type(fill_value)):
                 pytest.xfail("mix of lack of upcasting, resp. wrong missing value")
 
     # special case for box_dtype