Reapply "[mlir][vector] Drop inner unit dims for transfer ops on dynamic shapes." (#80712) (#81778)

This reverts commit b4c7152e.

Downstream regression due to another issue that this PR exposes. We have identified the work-items to fix the new issue here: https://github.com/openxla/iree/issues/16406



Co-authored-by: Han-Chung Wang <hanchung@google.com>