[mlir] Remove unnecessary canonicalization from Linalg Detensorize.cpp

After https://reviews.llvm.org/D115821 it became possible to create
`tensor<elem_type>` with a single `tensor.from_elements` operation without
collapsing tensor shape from `tensor<1xelem_type>` to `tensor<elem_type>`

Differential Revision: https://reviews.llvm.org/D115891