[mlir][NFC] Clean up builder usage around constants/non-foldable ops

* Use `create` instead of `createOrFold` for constant ops. Constants cannot be folded any further.
* Use `create` instead of `createOrFold` for ops that do not have a folder.
* Use C++ op builders that take an `int` instead of creating a `ConstantIndexOp`.
* Create `tensor::DimOp` instead of `linalg::createOrFoldDimOp` when it is certain that the operand is a tensor.

Differential Revision: https://reviews.llvm.org/D154196