Refactor OpenAI completion module test to restore original module state

- Added logic to save and restore the original OpenAI completion module during the test to prevent issues with class re-imports affecting subsequent tests.
- Ensured that the test checks for the presence of the module and its attributes only after the module is properly reloaded.
- Improved test reliability by avoiding potential failures due to module state changes across tests.

lib/crewai/tests/llms/openai/test_openai.py

@@ -134,14 +134,13 @@ def test_openai_is_default_provider_without_explicit_llm_set_on_agent():
 
 
 
-def test_openai_completion_module_is_imported():
+def test_openai_completion_module_is_imported(monkeypatch):
     """
     Test that the completion module is properly imported when using OpenAI provider
     """
     module_name = "crewai.llms.providers.openai.completion"
 
-    if module_name in sys.modules:
-        del sys.modules[module_name]
+    monkeypatch.delitem(sys.modules, module_name, raising=False)
 
     LLM(model="gpt-4o")