fix: drop invalid qualified_name kwarg and annotate tests for mypy

- Remove 8 qualified_name="..." kwargs passed to FunctionToOptimize:
  qualified_name is a @Property, not a constructor field. Pydantic silently
  accepts it at runtime but mypy strict mode (prek hook) rejects it.
- Add -> None return annotations and missing Path / JavaSupport parameter
  annotations to every test method + fixture in test_replacement.py so the
  prek mypy hook passes when the file is in the CI diff.

Author: mohamedashrraf222