[clang] Suppress printing lambda body for constexpr diagnostics (PR #185800)

[Sherman Pay via cfe-commits]

shermpay wrote:

> > I have squashed the commits into a single commit via fixups. I think this is ready for submission. PTAL.
> 
> For future reference, this is actually undesirable as it messes up with Github. Once a PR lands, we merge with squash (and the pr description becomes the commit message)

I see. I got the impression that was the preferred method from https://llvm.org/docs/GitHub.html#landing-your-change

> [Interactive rebase](https://git-scm.com/docs/git-rebase#_interactive_mode) with fixups. This is the recommended method since you can control the final commit message and check that the final commit looks as you expect. When your local state is correct, remember to force-push to your branch and press the merge button in GitHub’s web interface afterwards.

Maybe the documentation is outdated? Anyways, I'll keep this in mind for future PRs, thanks!

https://github.com/llvm/llvm-project/pull/185800