[FlexAttention] PassManager::run failed during running FlexAttention UT

[yudongsi]

Describe the bug

There are some remaining ut faliures: #3929 (comment)

python ../pytorch/test/inductor/test_flex_attention.py TestFlexAttentionXPU.test_load_from_bias_head_seq_batch_float16_xpu_float16 # run failed, LoadStoreOpToLLVM.cpp:920 / llvm_unreachable("unexpected OpIdx::OperandC"); 
python ../pytorch/test/inductor/test_flex_attention.py TestFlexAttentionXPU.test_load_from_bias_seq_batch_float16_xpu_float16 # run failed, LoadStoreOpToLLVM.cpp:920 / llvm_unreachable("unexpected OpIdx::OperandC"); 
python ../pytorch/test/inductor/test_flex_attention.py TestFlexAttentionXPU.test_load_from_bias_seq_only_float16_xpu_float16 # run failed, LoadStoreOpToLLVM.cpp:920 / llvm_unreachable("unexpected OpIdx::OperandC"); 

Environment details

pytorch/13339ce0869 with the patch from PR pytorch/pytorch#143553
triton latest

Fix patch prepared locally.

[yudongsi]

Closing as duplicate of #4059.