We need to skip internet access on offline installation.
To do this we need following changes:
- prevent running yum/apt for each script
- set default "NO" for scripts it requires package installation
- set default "NO" for scripts it requires internet access, such as NTP
See #7153Closes#7224
* syuu1228-offline_setup:
dist/common/scripts: skip internet access on offline installation
scylla_ntp_setup: use shutil.witch() to lookup command
12ca7f7ace