LSF Integration: When A user picks a profile, an error appears, "bsub not found"

Bug description

LSF Integration: When A user picks a profile, an error appears, "bsub not found". Now each user can use bsub if they drop to the terminal. So it's in their path and they can execute it.

Expected behaviour

I expect the user to pick the machine profile they want and then open a jupyterhub session

Actual behaviour

The error "bsub not found" appears and the user must pick a local session.

How to reproduce

Login and pick a a profile.

Your personal set up

Using jupyterlab as the default gui
jupyterhub v1.3.0
python v3.8.1
jupyterlab==3.0.9
jupyterlab-server==2.3.0

• OS:
  CentOS Linux release 7.9.2009 (Core)

c.JupyterHub.spawner_class = 'wrapspawner.ProfilesSpawner'
c.Spawner.http_timeout = 120

c.JupyterHub.bind_url = 'https://:443'
import batchspawner
c.JupyterHub.spawner_class = 'wrapspawner.ProfilesSpawner'
c.Spawner.http_timeout = 120
c.BatchSpawnerBase.req_host = 'mesabi.xyz.edu'
c.BatchSpawnerBase.req_runtime = '12:00:00'
c.LsfSpawner.state_exechost_exp = r'in-\1.mesabi.xyz.edu'
c.ProfilesSpawner.profiles = [
( "Local server", 'local', 'jupyterhub.spawner.LocalProcessSpawner', {'ip':'0.0.0.0'} ),
('BBL - 2 cores, 4 GB, 8 hours', 'bbl2c4g8h', 'batchspawner.LsfSpawner',
dict(req_nprocs='2', req_queue='mesabi_normal', req_runtime='8:00:00', req_memory='4gb')),
('BBL - 4 cores, 8 GB, 4 hours', 'bbl4c8g4h', 'batchspawner.LsfSpawner',
dict(req_nprocs='12', req_queue='bbl_normal', req_runtime='4:00:00', req_memory='8b')),
('BBL - 8 cores, 12 GB, 24 hours', 'bbl8c12g24h', 'batchspawner.LsfSpawner',
dict(req_nprocs='2', req_queue='bbl_normal', req_runtime='24:00:00', req_memory='12gb')),
('Interactive BBL - 2 cores, 4 GB, 8 hours', 'lab', 'batchspawner.LsfSpawner',
dict(req_nprocs='2', req_host='labhost.xyz.edu', req_queue='bbl_interactive',
req_runtime='8:00:00', req_memory='4gb', state_exechost_exp='')),
]
c.ProfilesSpawner.ip = '0.0.0.0'
c.JupyterHub.ssl_cert = '/etc/pki/tls/certs/someting.cer'
c.JupyterHub.ssl_key = '/etc/pki/tls/private/something.key'
c.Spawner.cmd=["jupyter-labhub"]
c.Spawner.env_keep = ['PATH', 'PYTHONPATH', 'CONDA_ROOT', 'CONDA_DEFAULT_ENV', 'VIRTUAL_ENV', 'LANG', 'LC_ALL', 'LD_LIBRARY_PATH']
c.PAMAuthenticator.group_whitelist = ("something, something",)
c.PAMAuthenticator.check_account = False
c.PAMAuthenticator.open_sessions = False

-->

• Logs

Error: HTTP 500: Internal Server Error (Error in Authenticator.pre_spawn_start: RuntimeError sudo: bsub: command not found)

Start at Authenticator.pre_spawn_start and the batchspawner.LsfSpawner profile configuration, then compare the environment used there with the user's terminal PATH. Reproduce the profile selection and inspect the logged sudo: bsub: command not found error. Done means selecting an LSF profile opens the requested JupyterHub session instead of falling back to a local session.