[clang] [clang] Fix high memory consumption during pack deduction (PR #88637)

[Matheus Izvekov via cfe-commits]

mizvekov wrote:

@term-est It would be helpful if you could post the surrounding code context where this crashed, This is pointed at the top of the stacktrace:
```
0.	/home/est/Working-Directory/DS/wetend-emulator-new/WetendEmulator.hpp:85:128: current parser token ')'
```

You said, and I confirm from the stack trace, it looks like this happened in a clangd invocation.
Does it also happen during compilation with clang?

Are you able to share prints and dumps from values surrounding the crash site?
Some examples:
```
NumNamedPacks
Info.getNumExplicitArgs()
Info.getDeducedDepth()
S.CurrentInstantiationScope != nullptr
PartialPackDepthIndex
Packs[...].Index
```



https://github.com/llvm/llvm-project/pull/88637