[functorch] Remove test/test_functorch_lagging_op_db.py (pytorch/functorch#845)

These tests are expected to fail, but we didn't communicate that very
well and:
1. we have gotten multiple questions about them
2. we need to special case it in our CI
3. we don't even use the test anymore!

So we are deleting it.

Related: https://github.com/pytorch/functorch/issues/835

functorch/test/test_functorch_lagging_op_db.py

@@ -1,38 +0,0 @@
-# Copyright (c) Facebook, Inc. and its affiliates.
-# All rights reserved.
-#
-# This source code is licensed under the BSD-style license found in the
-# LICENSE file in the root directory of this source tree.
-from torch.testing._internal.common_methods_invocations import op_db
-from torch.testing._internal.common_device_type import (
-    instantiate_device_type_tests,
-    ops,
-)
-from torch.testing._internal.common_utils import TestCase, run_tests
-from functorch_lagging_op_db import (
-    functorch_lagging_op_db,
-    in_functorch_lagging_op_db,
-)
-import torch
-
-
-class TestFuncTorchLaggingOpDb(TestCase):
-    def test_functorch_lagging_op_db_has_opinfos(self, device):
-        self.assertEqual(len(functorch_lagging_op_db), len(op_db))
-
-    @ops(op_db, allowed_dtypes=(torch.float,))
-    def test_coverage(self, device, dtype, op):
-        if in_functorch_lagging_op_db(op):
-            return
-        raise RuntimeError(
-            f"{(op.name, op.variant_test_name)} is in PyTorch's OpInfo db ",
-            "but is not in functorch's OpInfo db. Please regenerate ",
-            "test/functorch_lagging_op_db.py and add the new tests to ",
-            "denylists if necessary.")
-
-
-instantiate_device_type_tests(
-    TestFuncTorchLaggingOpDb, globals(), only_for=['cpu'])
-
-if __name__ == '__main__':
-    run_tests()