Fix index of the result of get_dtype_counts (#308)

* Remove mapping index to numpy type and keep as string

* Remove sorting of index for get_dtype_counts

* Update get_dtype_counts test

modin/pandas/dataframe.py

@@ -1672,8 +1672,6 @@ def get_dtype_counts(self):
         """
         result = self.dtypes.value_counts()
         result.index = result.index.map(lambda x: str(x))
-        result = result.sort_index()
-        result.index = result.index.map(lambda x: np.dtype(getattr(np, x)))
         return result
 
     def get_ftype_counts(self):

modin/pandas/test/test_dataframe.py

@@ -993,7 +993,9 @@ def test_get(ray_df, pandas_df, key):
 
 @pytest.fixture
 def test_get_dtype_counts(ray_df, pandas_df):
-    assert ray_df.get_dtype_counts().equals(pandas_df.get_dtype_counts())
+    ray_result = ray_df.get_dtype_counts().sort_index()
+    pandas_result = pandas_df.get_dtype_counts().sort_index()
+    assert ray_result.equals(pandas_result)
 
 
 @pytest.fixture