fix(local): report owned container removal failures

[bobbyroach]

Summary

Report failed Docker removal for local sandboxes that own a container, including reattached sandboxes.

Motivation

docker rm -f ... || true made a Docker daemon failure look like successful teardown, potentially leaving a container and its host port behind.

Solution

Ignore only Docker's No such container response for owned containers. Preserve best-effort removal for VM-only sandboxes and still attempt Compose teardown when container removal fails.

Test plan

• Reproduced the masked failure before the fix with Docker pointed at a nonexistent local socket; after the fix, teardown raises in both live and reattached modes.
• .venv/bin/pytest -q tst/unit/providers/sandbox_providers/local_sandbox_test.py tst/unit/task/teardown_test.py — 82 passed.
• git diff --check passed.