Slurm tests improve SSH

[mr0re1]

• Ensure that tunnel is established instead of sleep;
• Monitor setup.log instead of sleep 2 minutes;

$ python3 tools/python-integration-tests/slurm_simple_job_completion.py --deployment-name=qq --project=io-playground --zone=us-central1-a --username=ext_orlov_google_com
...
INFO:root:Waiting for login node setup:
...
INFO:root:setup.log: 2025-05-30 21:51:54,119 INFO: Check status of cluster services
INFO:root:setup.log: 2025-05-30 21:51:54,149 INFO: Done setting up login
...
JobID 79 finished successfully.
JobID 80 finished successfully.
JobID 81 finished successfully.
JobID 82 finished successfully.
JobID 83 finished successfully.
.
----------------------------------------------------------------------
Ran 1 test in 19.147s

OK

$ bbs 4239 --names "PR-test-slurm-gcp-v6-reconfig-size" "PR-test-slurm-gcp-v6-simple-job-completion" "PR-test-slurm-flex" "PR-test-slurm-gcp-v6-topology" -c 5
Using PR#4239: Slurm tests improve SSH