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

[Hans Wennborg via cfe-commits]

zmodem wrote:

Is there anything we can do to make this change less disruptive going forward?

Should some Clang experts review the relands? Is there more testing that could be done? Is there any chance of breaking it into smaller patches?

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