fix: set PYTHONDONTWRITEBYTECODE=1 in container to prevent root-owned __pycache__

Python inside the container writes __pycache__/*.pyc as root (container user).
This causes PermissionError during tempfile cleanup in CI docker integration tests.
Setting PYTHONDONTWRITEBYTECODE=1 suppresses .pyc generation entirely, which is
appropriate for a build-tool container that has no need for bytecode caching.

Co-Authored-By: Oz <oz-agent@warp.dev>

Author: tbitcs

west_env/container.py

@@ -48,6 +48,8 @@ def _container_args(cfg, command, interactive=False, workspace=None, host_cwd=No
         container_wd,
         "-e",
         "PYTHONPATH=/work/modules/west-env",
+        "-e",
+        "PYTHONDONTWRITEBYTECODE=1",
     ]
 
     if interactive: