[clang] [Serialization] Fix lazy template loading (PR #133057)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> > Thanks for waiting! I ran a build of most of our code with this PR and didn't find any issues.
> 
> Great! In that case, I would like to proceed with landing the commits individually so they can be more easily reverted if needed (see discussion at the beginning of the PR), and then we can see if we can / want to backport for `release/22.x`. Please object if you see a problem with that plan.

As this patch doesn't add any new functionalities. I think we don't need to backport it.

https://github.com/llvm/llvm-project/pull/133057