fix: remove test_root_and_prefix_mutual_exclusive

It is made incorrect by the previous commit.

Author: mcepl

Lib/test/test_ensurepip.py

@@ -110,11 +110,6 @@ def test_bootstrapping_with_prefix(self):
             unittest.mock.ANY,
         )
 
-    def test_root_and_prefix_mutual_exclusive(self):
-        with self.assertRaises(ValueError):
-            ensurepip.bootstrap(root="", prefix="")
-        self.assertFalse(self.run_pip.called)
-
     def test_bootstrapping_with_user(self):
         ensurepip.bootstrap(user=True)