…oin plans (apache#21947)

Closes apache#21946

`adjust_input_keys_ordering` returns `Transformed::yes` unconditionally
in the default else branch, even when `requirements.data` is empty and
no changes were made. This triggers unnecessary `with_new_children`
rebuilds on every node in the plan tree for non-join/non-aggregate
queries.

For plans with custom `ExecutionPlan` nodes whose `with_new_children` is
expensive (e.g. nodes that re-evaluate cost functions on rebuild), this
causes significant overhead.

Add an early return with `Transformed::no` when
`requirements.data.is_empty()` in the default else branch of
`adjust_input_keys_ordering`. This skips the unnecessary plan tree
rebuild for simple scan/filter/limit plans that have no join key
reordering requirements.

Yes, two unit tests added:
- `adjust_input_keys_ordering_no_transform_for_scan` — verifies a bare
parquet scan returns `Transformed::no`
- `adjust_input_keys_ordering_no_transform_for_filter_scan` — verifies a
filter→scan tree returns `Transformed::no` via `transform_down`

No. This is a performance optimization that does not change query
results or plan structure.

(cherry picked from commit 05a6c45)