[clang] [CGExprConstant] stop calling into ConstExprEmitter for Reference type destinations (PR #70366)

[Bernhard Rosenkraenzer via cfe-commits]

berolinux wrote:

Might be good to backport this to 17.x, given the regression was introduced on the 17 branch after 17.0.0

https://github.com/llvm/llvm-project/pull/70366