[lldb] Don't rely on ScriptInterpreterPythonImpl::Initialize in the unit tests (llvm#82096)

The unit tests only test the Python objects and don't actually use
anything from the LLDB module. That means that all the additional
complexity in ScriptInterpreterPythonImpl::Initialize is overkill.

By doing the initialization by hand, we avoid the annoying
ModuleNotFoundError.

  Traceback (most recent call last):
    File "<string>", line 1, in <module>
  ModuleNotFoundError: No module named 'lldb'

The error is the result of us stubbing out the SWIG (specifically
`PyInit__lldb`) because we cannot link against libLLDB from the unit
tests.

The downside of doing the initialization manually is that we do lose a
bit of test coverage. For example, issue llvm#70453 also manifested itself
in the unit tests.

(cherry picked from commit 5c96e71)

Author: JDevlieghere

lldb/unittests/ScriptInterpreter/Python/PythonTestSuite.cpp

@@ -9,42 +9,26 @@
 #include "gtest/gtest.h"
 
 #include "Plugins/ScriptInterpreter/Python/SWIGPythonBridge.h"
-#include "Plugins/ScriptInterpreter/Python/ScriptInterpreterPython.h"
-#include "Plugins/ScriptInterpreter/Python/ScriptInterpreterPythonImpl.h"
 #include "Plugins/ScriptInterpreter/Python/lldb-python.h"
 
-#include "lldb/Host/FileSystem.h"
-#include "lldb/Host/HostInfo.h"
-
 #include "PythonTestSuite.h"
 
-using namespace lldb_private;
-class TestScriptInterpreterPython : public ScriptInterpreterPythonImpl {
-public:
-  using ScriptInterpreterPythonImpl::Initialize;
-};
-
 void PythonTestSuite::SetUp() {
-  FileSystem::Initialize();
-  HostInfoBase::Initialize();
-  // ScriptInterpreterPython::Initialize() depends on HostInfo being
-  // initializedso it can compute the python directory etc.
-  TestScriptInterpreterPython::Initialize();
-
   // Although we don't care about concurrency for the purposes of running
   // this test suite, Python requires the GIL to be locked even for
   // deallocating memory, which can happen when you call Py_DECREF or
   // Py_INCREF.  So acquire the GIL for the entire duration of this
   // test suite.
+  Py_InitializeEx(0);
   m_gil_state = PyGILState_Ensure();
+  PyRun_SimpleString("import sys");
 }
 
 void PythonTestSuite::TearDown() {
   PyGILState_Release(m_gil_state);
 
-  TestScriptInterpreterPython::Terminate();
-  HostInfoBase::Terminate();
-  FileSystem::Terminate();
+  // We could call Py_FinalizeEx here, but initializing and finalizing Python is
+  // pretty slow, so just keep Python initialized across tests.
 }
 
 // The following functions are the Pythonic implementations of the required