[clang] [Clang] Fix an integer overflow issue in computing CTAD's parameter depth (PR #128704)

[Haojian Wu via cfe-commits]

hokein wrote:

> > Need to add a release note as it fixes an existing issue.
> 
> Do you think we need a backport? If so, we can add the release note in the backport PR

This is not a regression, but we have a change in clang20 which exposes this issue in the assertion-build clang. I'd prefer a backport.

https://github.com/llvm/llvm-project/pull/128704