Enable test sparse allreduce basics Windows (pytorch#103317)

The test was marked as flaky in pytorch#59965. However, it is not failing anymore so it can be enabled.

This PR enables only one test, but it will only run in local tests because the test suite is disabled in CI.

pytorch#94495 is a superset of this PR which enables the full test suite. The CI run there shows this test passing.

Fixes pytorch#59965
Pull Request resolved: pytorch#103317
Approved by: https://github.com/kit1980

test/distributed/test_c10d_gloo.py

@@ -693,7 +693,6 @@ def _test_sparse_allreduce_basics(self, fn):
                 self.assertEqual(tensors, outputs)
                 self.assertEqual(result, outputs)
 
-    @skip_but_pass_in_sandcastle("intermittent failures on Windows, in CI")
     @requires_gloo()
     def test_sparse_allreduce_basics(self):
         self._test_sparse_allreduce_basics(lambda t: t)