[clang] [llvm] [mlir] [Clang][CodeGen] Start migrating away from assuming the Default AS is 0 (PR #88182)

[Alexander Richardson via llvm-commits]

https://github.com/arichardson commented:

Spotted one more duplicate test, otherwise looks good to me with the reworded TODO comment suggestion.

https://github.com/llvm/llvm-project/pull/88182