pylint: Drop no longer used __home

`__home` has been added in 8ca44bcbfa,
later `tests.util` was refactored in
fd43b39145, but `__home` wasn't cleaned
up.

Fixes: https://pagure.io/freeipa/issue/9117
Signed-off-by: Stanislav Levin <slev@altlinux.org>
Reviewed-By: Rob Crittenden <rcritten@redhat.com>

ipatests/util.py

@@ -146,7 +146,6 @@ class TempDir:
 class TempHome(TempDir):
     def __init__(self):
         super(TempHome, self).__init__()
-        self.__home = os.environ['HOME']
         os.environ['HOME'] = self.path