`getTypeSourceInfo()->getType()` and `getType()` are inconsistent for a constrained variable

[tJener]

#include <concepts>

void find(auto value) {
  std::integral auto var = value;
}

Calling getTypeSourceInfo()->getType() and getType() result in two unique AutoTypes. If I have something like

v.getTypeSourceInfo()->getType()->dump();
v.getType()->dump();

the output is

AutoType 0x141b92c00 'integral auto' undeduced
`-Concept 0x141995a88 'integral'
AutoType 0x141b92d30 'integral auto' dependent
`-Concept 0x141995a88 'integral'

[llvmbot]

@llvm/issue-subscribers-clang-frontend

Author: Eric Li (tJener)

```c++ #include <concepts>

void find(auto value) {
std::integral auto var = value;
}

Calling `getTypeSourceInfo()->getType()` and `getType()` result in two unique `AutoType`s. If I have something like
```c++
v.getTypeSourceInfo()->getType()->dump();
v.getType()->dump();

the output is

AutoType 0x141b92c00 'integral auto' undeduced
`-Concept 0x141995a88 'integral'
AutoType 0x141b92d30 'integral auto' dependent
`-Concept 0x141995a88 'integral'

[shafik]

CC @mizvekov