caucase.test: Rename shell test to something easier to understand.

It is redundant, but regular runner output does not display the test class.

caucase/test.py

@@ -3188,7 +3188,7 @@ class CaucaseShellTest(unittest.TestCase):
       )
     )
 
-  def test_test(self):
+  def test_shell_test(self):
     """
     Run caucase.sh's embedded testsuite.
     """