clean-up: consider removing domain schedule from tensor_ext.assign_layout

[asraa]

The domain schedule attribute was intended to reduce the complexity of the ISL loop generation by providing extra domain vars to add to the schedule. This would make the loop execution time longer, but significantly speed up compilation time.

We've added an option to construct a list of layouts to construct to speed up compilation time, and it is likely that the domainschedule attr is no longer needed.