Fix flaky ET attention test #6795
                
     Merged
            
            
          
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Summary
Torch's manual seed is environment-based,
loosen the tol for torch.allcloseuse assert_close instead which sets an appropriate atol and rtol based on the dtype, since the previous tol was too strict.Fixes flaky mha test and reverts #6790.
Test plan
Confirmed and reproduced locally by altering the manual seed until there was an issue. Modified unit test to pass locally.