CLN: Fix all flake8 warnings in pandas/tests

Ouch my wrists. I will rebase and fix the post-rebase entropy
tomorrow.

Author: Wes McKinney <[email protected]>

Closes #12069 from wesm/style/flake8-pandas-tests and squashes the following commits:

588b255 [Wes McKinney] STY: Fix pandas/tests flake8 warnings and disable qa on difficult modules

Author: wesm

pandas/tests/frame/test_operators.py

@@ -477,7 +477,7 @@ def test_binary_ops_align(self):
             result = getattr(df, op)(x, level='second', axis=0)
 
             expected = (pd.concat([opa(df.loc[idx[:, i], :], v)
-                                  for i, v in x.iteritems()])
+                                   for i, v in x.iteritems()])
                         .reindex_like(df).sortlevel())
             assert_frame_equal(result, expected)