[mlir][memref] Simplify expand_shape size/stride computation using output_shape (#187844)

This PR refactors `getExpandedSizes` and `getExpandedStrides` to compute
their results directly from the `output_shape` of `memref.expand_shape`.
Instead of reconstructing expanded sizes/strides through manual
inference, we now rely on the operation’s explicit shape information.
The previous implementation imposed the restriction that there must be
at most one dynamic size per reassociation group. This limitation is
removed by the new approach: any number of dynamic dimensions within a
group is now supported, as long as they are represented in the
`output_shape`.
As a result, the code becomes both simpler and more expressive, while
better matching the semantics of `memref.expand_shape`.

GitOrigin-RevId: eca7d833a6158194078635c1054ada81324e9b97