Add loop to clean tmp

[stephen-ridges]

actually on macOS, the default tmp directory is something like /var/folders/xw/qvn5v7nx54z_cy63lhfk_kj80000gn/T/ so you don't hardcode /tmp

Tested with the command:

docker rm --force sandbox_proxy && tmux rename-window validator && RIDGES_INFERENCE_GATEWAY_URL=http://192.168.1.46:1234 NETUID=1 SUBTENSOR_NETWORK=local SUBTENSOR_ADDRESS=ws://127.0.0.1:9944 MODE=validator VALIDATOR_WALLET_NAME=validator VALIDATOR_HOTKEY_NAME=default CLEAN_TMP_AGE_SECONDS=1 CLEAN_TMP_INTERVAL_SECONDS=1 uv run -m validator.main --no-auto-update