Avoid shell escaping command_prefix

[omus]

Probably will end up being a dumping ground for various small changes to support multi-node clusters

Update: Was the only required backend change to get multi-node support working.

[omus]

Noticed this issue with out multi-node setup:

2023-09-18 08:00:50,586 DEBUG context.py:49 -- deserialize: {'command_prefix': ['cd', '/tmp/ray/session_2023-09-18_07-59-14_737958_8/runtime_resources/working_dir_files/_ray_pkg_4136a847bed2407b', '&&'], 'env_vars': {'RAY_EXPERIMENTAL_NOSET_CUDA_VISIBLE_DEVICES': '1', 'RAY_worker_niceness': '0', 'PYTHONPATH': '/tmp/ray/session_2023-09-18_07-59-14_737958_8/runtime_resources/working_dir_files/_ray_pkg_4136a847bed2407b'}, 'py_executable': '/home/ray/anaconda3/bin/python', 'resources_dir': None, 'container': {}, 'java_jars': [], 'julia_command': []}
2023-09-18 08:00:50,586 DEBUG context.py:54 -- Worker context env: {'RAY_EXPERIMENTAL_NOSET_CUDA_VISIBLE_DEVICES': '1', 'RAY_worker_niceness': '0', 'PYTHONPATH': '/tmp/ray/session_2023-09-18_07-59-14_737958_8/runtime_resources/working_dir_files/_ray_pkg_4136a847bed2407b'}
2023-09-18 08:00:50,586 DEBUG context.py:94 -- Exec'ing worker with command: cd /tmp/ray/session_2023-09-18_07-59-14_737958_8/runtime_resources/working_dir_files/_ray_pkg_4136a847bed2407b '&&' exec /home/ray/anaconda3/bin/python /home/ray/anaconda3/lib/python3.10/site-packages/ray/_private/workers/default_worker.py --node-ip-address=10.0.17.45 --node-manager-port=45277 --object-store-name=/tmp/ray/session_2023-09-18_07-59-14_737958_8/sockets/plasma_store --raylet-name=/tmp/ray/session_2023-09-18_07-59-14_737958_8/sockets/raylet --redis-address=None --temp-dir=/tmp/ray --metrics-agent-port=51035 --logging-rotate-bytes=536870912 --logging-rotate-backup-count=5 --gcs-address=10.0.17.45:6379 --session-name=session_2023-09-18_07-59-14_737958_8 --temp-dir=/tmp/ray --webui=10.0.17.45:8265 --startup-token=0 --worker-launch-time-ms=1695049250195 --runtime-env-hash=-2080361810
bash: line 0: cd: too many arguments

It appears that we quoted too much of the command in #8