[clang] [clang] fix broken canonicalization of DeducedTemplateSpecializationType (PR #95202)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

It still fixes the original bug report though.

Otherwise adding a test which directly tests all observable effects of the profiling fix would be a bit arbitrary, as we don't have any unit tests for the gazillion ways this could go wrong for the other AST nodes.

This usually gets caught incidentally in diagnostics for unrelated tests. In this case that incidental test was in libc++.

https://github.com/llvm/llvm-project/pull/95202