LMS-2471 bugs fixed, making scripts more robust

...is_all/source/bash/check-and-exit-if-new-sprint-server.sh

openbis_all/source/bash/create-config-snapshot.sh

openbis_all/source/bash/create-generic-snapshot.sh

openbis_all/source/bash/create-snapshot.sh

openbis_all/source/bash/create-sprint-screening-snapshot.sh

openbis_all/source/bash/fetch-ci-artifacts.sh

..._all/source/bash/fetch-generic-sprint-server-artifacts.sh

...ll/source/bash/fetch-screening-sprint-server-artifacts.sh

openbis_all/source/bash/install-servers.sh

openbis_all/source/bash/nightly-upgrade-generic-openbis.sh

openbis_all/source/bash/nightly-upgrade-screening-openbis.sh

openbis_all/source/bash/servers-shutdown.sh

...s_all/source/bash/servers-startup-from-latest-snapshot.sh

openbis_all/source/bash/servers-startup-from-snapshot.sh

openbis_all/source/bash/servers-startup.sh