Avoid python tracebacks in output during provisioning

[rocodes]

• I have searched for duplicates or related issues
• Related (these could make a story/epic):
  • Address (or suppress) warning messages and/or information displayed in terminal output: Warning message during provisioning indicates we're not creating qubes-appmenus entry for send-to-usb.desktop #1123 , Silence [CRITICAL] Specific ext_pillar interface qvm_prefs is unavailable errors #747 , Suppress sensitive information in terminal output during make all #417
  • Catch logic errors and don't provision, or bail early: Running sdw-admin --appl (typo) still provisions #1071 , provision-all should fail if salt commands return an error. #232
  • Logic: securedrop-workstation-bullseye template install fails after uninstall #813

Description

Per #1205 (comment), consider showing a friendlier warning instead of a python traceback in provision-all or other admin scripts.

How will this impact SecureDrop/SecureDrop Workstation users?

Easier to understand terminal output. (Potentially harder to debug if there is an issue, but we can address.)

How would this affect the SecureDrop Workstation threat model?

this issue: n/a. Linked issues: be sure not to write sensitive info to console.

[deeplow]

@rocodes should we add to the scope python tracebacks during sdw-admin --validate?