[llvm] [NFC][SystemZ] Update insert() API of the AssociatedDataAreaTable class (PR #174593)

[Tony Tao via llvm-commits]

================

----------------
tltao wrote:

We can emit a comment here to help with debugging now that we have a symbol name. E.g.
```
OutStreamer->AddComment(Twine("Load ")
                            .concat(Sym->getName())
                            .concat(Offset ? "+" + utostr(Offset) : "")
                            .concat(" from offset ")
                            .concat(utostr(Disp)));
```

https://github.com/llvm/llvm-project/pull/174593