[lldb] Fix pid_t redefinition on Windows in ScriptInterpreterPythonInterfaces (#181492)
## Summary
- Move `#include "lldb/Core/PluginManager.h"` after `#include
"ScriptInterpreterPythonInterfaces.h"` so Python's `pyconfig.h` defines
`pid_t` before `PosixApi.h` gets included. This fixes the `C2371:
'pid_t': redefinition; different basic types` error on all Windows
builders.
Fixes CI failures from #181334 / #181488.
Co-authored-by: Rahul Reddy Chamala <rachamal@meta.com>