[clang] [Clang] skip default argument instantiation for non-defining friend declarations without specialization info to meet [dcl.fct.default] p4 (PR #113777)

[Alan Zhao via cfe-commits]

alanzhao1 wrote:

Based on the [patch reversion policy](https://llvm.org/docs/DeveloperPolicy.html#patch-reversion-policy), I think reverting is the right thing to do.

(I'm working on the reduced repro, but creduce is _really_ slow. In the meantime, I attached the unreduced files). 

[unreduced.tar.gz](https://github.com/user-attachments/files/17671006/unreduced.tar.gz)

https://github.com/llvm/llvm-project/pull/113777