The 'TargetAttr' workflow was recently introduced to serialization for
'MLIR->LLVM->PTX'. #65857 removes previous passes (gpu::Serialization*
passes) because they are duplicates.
This PR removes the use of gpu::Serialization* passes in SM_90
integration tests, and enables the 'TargetAttr' workflow.
It also moves the transform dialect specific test to a new folder.
ad4411230a