[clang] [CIR] Fix assertion on wide string with large code unit (PR #228430)

[Erich Keane via cfe-commits]

erichkeane wrote:

This is a duplicate here: https://github.com/llvm/llvm-project/pull/228101

Also, you've done this with AI in violation of our AI policy, so I'm just going to close this one.

https://github.com/llvm/llvm-project/pull/228430