[llvm] [SeparateConstOffsetFromGEP] Reland: Reorder trivial GEP chains to separate constants (PR #81671)

[Krzysztof Drewniak via llvm-commits]

https://github.com/krzysz00 approved this pull request.

Re-land approved on the assumption that this is all the test fixes

https://github.com/llvm/llvm-project/pull/81671