[libcxx] [test] Remove a leftover unused function in config.py. NFC.

While there's little value in polishing the old config system,
I ran into this function and was confused for a while, while grepping
around and trying to wrap my head around things.

Differential Revision: https://reviews.llvm.org/D116131

libcxx/utils/libcxx/test/config.py

@@ -160,14 +160,6 @@ class Configuration(object):
         self.lit_config.note("Linking against the ABI Library at {}".format(self.abi_library_root))
         self.lit_config.note("Running against the ABI Library at {}".format(self.abi_runtime_root))
 
-    def get_test_format(self):
-        from libcxx.test.format import LibcxxTestFormat
-        return LibcxxTestFormat(
-            self.cxx,
-            self.use_clang_verify,
-            self.executor,
-            exec_env=self.exec_env)
-
     def configure_cxx(self):
         # Gather various compiler parameters.
         cxx = self.get_lit_conf('cxx_under_test')