Remove unnecessary setUp

setUp will be automatically called around each
testcase, so this is to remove setUp that doing
nothing additional than super to keep code clean.

Change-Id: I47be2be6f0e9785eb166f89d411582d6292babc1

openstackclient/tests/unit/test_shell.py

@@ -413,9 +413,6 @@ class TestShellCli(TestShell):
 class TestShellArgV(TestShell):
     """Test the deferred help flag"""
 
-    def setUp(self):
-        super(TestShellArgV, self).setUp()
-
     def test_shell_argv(self):
         """Test argv decoding