Revert "[lldb] Make use of Scripted{Python,}Interface for ScriptedThreadPlan (#70392)"

This reverts commit 4b3cd379cc since it
introduces some test failures:

https://lab.llvm.org/buildbot/#/builders/68/builds/62556

lldb/source/Plugins/ScriptInterpreter/Python/Interfaces/ScriptedPlatformPythonInterface.cpp

@@ -20,8 +20,6 @@
 #include "../ScriptInterpreterPythonImpl.h"
 #include "ScriptedPlatformPythonInterface.h"
 
-#include "lldb/Target/ExecutionContext.h"
-
 using namespace lldb;
 using namespace lldb_private;
 using namespace lldb_private::python;