[clang] [clang] Remove separate evaluation step for static class member init. (PR #142713)

[Shafik Yaghmour via cfe-commits]

https://github.com/shafik commented:

So just to confirm my reading, this is benefiting from `CheckCompleteVariableDeclaration` doing:

```cpp
  // Evaluate the initializer to see if it's a constant initializer.
  HasConstInit = var->checkForConstantInitialization(Notes);
```

or is there more?

https://github.com/llvm/llvm-project/pull/142713