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

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

I have an admin question first: is this there an issue for this in the bug tracker? I am only asking because we have quite a few sitting in there and I was trying to get an overview, and was wondering if this patch addresses one. 

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