[llvm] [DA] remove constraint propagation and coupled/separable subscripts (PR #160924)

[Sebastian Pop via llvm-commits]

sebpop wrote:

> To be clear: I _am_ happy with this direction -- it's an alternative to NewDA

I'm happy that we can find a middle ground where we can focus on moving forward.

https://github.com/llvm/llvm-project/pull/160924