run_unittests: remove double definition of the same test case

In commit 591e6e94b9 we somehow ended up
with an identical extra copy.

run_unittests.py

@@ -8632,22 +8632,6 @@ class NativeFileTests(BasePlatformTests):
         else:
             self.fail('Did not find bindir in build options?')
 
-    def test_builtin_options_paths_legacy(self):
-        testcase = os.path.join(self.common_test_dir, '1 trivial')
-        config = self.helper_create_native_file({
-            'built-in options': {'default_library': 'static'},
-            'paths': {'bindir': 'bar'},
-        })
-
-        self.init(testcase, extra_args=['--native-file', config])
-        configuration = self.introspect('--buildoptions')
-        for each in configuration:
-            if each['name'] == 'bindir':
-                self.assertEqual(each['value'], 'bar')
-                break
-        else:
-            self.fail('Did not find bindir in build options?')
-
 
 class CrossFileTests(BasePlatformTests):