fix(Server Backup Management): print valid JSON/YAML output for list cmds#1379

rubenhoenle merged 2 commits intostackitcloud:mainstackitcloud/stackit-cli:mainfrom

j1n-o9r:fix/STACKITCLI-386-server-backup-json-list-outputj1n-o9r/stackit-cli:fix/STACKITCLI-386-server-backup-json-list-outputCopy head branch name to clipboard