[clang] [clang][Sema] Avoid out-of-memory crash on huge designated initializer indices (PR #205503)

[Max Manolov via cfe-commits]

maxmanolov wrote:

Thanks, I made both fixes: removed the non-configurable allocation ceiling and unwrapped the release-note entry. I also removed the high-limit test invocation that depended on the removed ceiling.

https://github.com/llvm/llvm-project/pull/205503