* [TIR] Remove ProducerConsumer and AllocateNode::new_expr
This PR removes two legacy IR parts in TIR that are deprecated.
ProducerConsumer node only serves as a hint markup and may no longer be
informative after extensive transformations in the pass.
If necessary, we can add related info via AttrStmt.
The new_expr field in the AllocateNode is deprecated since it can just be
replaced by a LetStmt.
- Remove dependencies of passes on ProducerConsumer.
- Remove ProducerConsumer from the IR.
- Remove the deprecated fields (new_expr, free_function) from AllocateNode.
* Fix additional testcases
