[c10d] Make test compatible for new pytest (pytorch#136158)

Temporary fix to the issue in pytorch#127517.

Short-term fix following CPython: https://github.com/python/cpython/blob/51aefc5bf907ddffaaf083ded0de773adcdf08c8/Lib/unittest/case.py#L419-L426

Differential Revision: [D62878083](https://our.internmc.facebook.com/intern/diff/D62878083)
Pull Request resolved: pytorch#136158
Approved by: https://github.com/fegin

Author: fduwjj

torch/testing/_internal/common_distributed.py

@@ -561,8 +561,14 @@ def __init__(self, method_name: str = "runTest", methodName: str = "runTest") ->
         if methodName != "runTest":
             method_name = methodName
         super().__init__(method_name)
-        fn = getattr(self, method_name)
-        setattr(self, method_name, self.join_or_run(fn))
+        try:
+            fn = getattr(self, method_name)
+            setattr(self, method_name, self.join_or_run(fn))
+        except AttributeError as e:
+            if methodName != 'runTest':
+                # we allow instantiation with no explicit method name
+                # but not an *incorrect* or missing method name
+                raise ValueError(f"no such test method in {self.__class__}: {methodName}") from e
 
     def setUp(self) -> None:
         super().setUp()
@@ -1014,8 +1020,14 @@ def __init__(self, method_name: str = "runTest", methodName: str = "runTest") ->
         if methodName != "runTest":
             method_name = methodName
         super().__init__(method_name)
-        fn = getattr(self, method_name)
-        setattr(self, method_name, self.join_or_run(fn))
+        try:
+            fn = getattr(self, method_name)
+            setattr(self, method_name, self.join_or_run(fn))
+        except AttributeError as e:
+            if methodName != 'runTest':
+                # we allow instantiation with no explicit method name
+                # but not an *incorrect* or missing method name
+                raise ValueError(f"no such test method in {self.__class__}: {methodName}") from e
 
     def perThreadSetUp(self):
         # super().setUp()  # TestCase.setUp() calls torch.manual_seed()