[clang] Revert "[Modules] Delay deserialization of preferred_name attribute at r…" (PR #123962)

[Ilya Biryukov via cfe-commits]

ilya-biryukov wrote:

Some benchmarks show an even bigger regression of up to 40% (although we're not sure if they're clear from noise).
We would want to look a little more into what's causing this and reland this in a way that does not cause significant regression or prove that it's impossible (hopefully that's not the case).

https://github.com/llvm/llvm-project/pull/123962