Fix lint issues and add parameter validation

- Remove unused Optional import from mlflow.py
- Add noqa comment for mlflow import in try block
- Add parameter type validation with TypeError for non-boolean inputs
- Add MLflow listener import to events/__init__.py
- Clean up unused imports in test files

Addresses code review feedback from João regarding parameter validation
and return type annotations while fixing CI lint failures.

Co-Authored-By: João <joao@crewai.com>

tests/test_mlflow_final.py

@@ -1,8 +1,7 @@
 """
 Final test for MLflow integration issue #2947
 """
-import pytest
-from unittest.mock import Mock, patch
+
 
 
 def test_mlflow_autolog_availability():