Revert "Apply clang-tidy fixes for misc-include-cleaner in IRCore.cpp (NFC)"

This reverts commit 0d109035.

Changes make Python bindings unbuildable without additional cmake
modifications (or modified `$PATH`).

```
/llvm-project/mlir/lib/Bindings/Python/IRCore.cpp:33:10: fatal error: 'funcobject.h' file not found
```

This header is provided by cpython, and we are not looking for that in
cmake.

Moreover, the nature of this change is not very clear to me. Seems to
replace one include with two dozens, presumably because the code is only
using transitively included headers, but the value for readability is
dubious. LLVM is also not strictly following IWYU.