[TIR][Schedule] Update compact_dataflow constraint

[Hzfengsy]

compact_dataflow is a very strong constraint, which requires all the blocks in the sub-AST to be complete or reduction blocks. Currently, there are two primitives that use such property:

• compute-at: the total scope is compact_dataflow.
• parallel/bind/vectorize: the total scope is compact_dataflow.

However, requiring all the scope to be compact_dataflow is too strict that some correct transformations are banned. (please see the added test cases). Here I updated the requirements:

• compute-at: only requires the input block is complete or reduction
• parallel/bind/vectorize: only requires compact_dataflow under the input loop.

cc @spectrometerHBH @junrushao1994 @vinx13