[clang] [Clang] Instantiate Typedefs referenced by type alias deduction guides (PR #111804)

[Younan Zhang via cfe-commits]

zyn0217 wrote:

I'll go ahead and backport it - this bug was first introduced by sugar preservation on CTAD guides included in the 19.x cycle.

/backport 0bc02b999a

https://github.com/llvm/llvm-project/pull/111804