clan-cli tests: remove dynamic inclusion of helpers module

Dynamically extending the python path at runtime is bad for developer experience, as this is not understood by the text editor and therefore jump to definition etc. does not work.

-> Better to remove the dynamic inclusion and force developers to specify the import correctly.

pkgs/clan-cli/tests/conftest.py

@@ -1,14 +1,8 @@
-import os
 import subprocess
-import sys
 from pathlib import Path
 
 import pytest
 
-sys.path.append(os.path.join(os.path.dirname(__file__), "helpers"))
-sys.path.append(str(Path(__file__).parent.parent))  # Also add clan_cli to PYTHONPATH
-
-
 from clan_cli.custom_logger import setup_logging
 from clan_cli.nix import nix_shell