[clang] [clang-tools-extra] [lldb] [clang] Reland: fix getTemplateInstantiationArgs (PR #208285)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

Correction, the reproducer in `https://ci.swift.org/job/llvm.org/job/clang-stage2-Rthinlto/job/main/402/` does not reproduce anything for me, it's a bad reproducer.

So as things stand now, this patch was reverted without any real actionable reason.

https://github.com/llvm/llvm-project/pull/208285