dedicated-env: Repeated attempts when the SSH connection is terminated

Instead of the usual execution of the script test_with_artifacts.sh via SSH, we extend the logic to handle situations related to the termination of the SSH connection.

• Run test command in background
• Reading test script log (tail -f) and reconnecting when SSH connection is interrupted

Fixed:

client_loop: send disconnect: Broken pipe

Example: https://gitlab.com/postgres-ai/postgresql-consulting/tests-and-benchmarks/-/jobs/6126396319

Additionally:

• improve conditions for pidstat artifacts
  • fixed: mv: cannot stat '/tmp/pidstat/*': No such file or directory