Improve hpc utils

[MehmedGIT]

Improvements:

• HPC (sbatch) job checks the Nextflow workflow exit status code to prevent false positives (i.e., the nextflow workflow fails, but no errors are raise)
• Always create new SFTP connections instead of checking the connectivity of the transport layer. The latter leads to false positives which leads to transfer connections failing to submit files to the HPC environment and failing the workers.
• Batch script readability increased