This PR fix the defect introduced by PR #1255 about the get-usage.sh call for bsmtp.
(bsmtp doesn't include CLI11 call like --help)

Please check

• Short description and the purpose of this PR is present above this paragraph
• Your name is present in the AUTHORS file (optional)

If you have any questions or problems, please give a comment in the PR.

Helpful documentation and best practices

• Git Workflow
• Automatic Sourcecode Formatting
• Check your commit messages

Checklist for the reviewer of the PR (will be processed by the Bareos team)

General

• PR name is meaningful
• Purpose of the PR is understood
• Commit descriptions are understandable and well formatted
• Check backport line
• Is the PR title usable as CHANGELOG entry?
• Separate commit for CHANGELOG.md ("update CHANGELOG.md"). The PR number is correct.

Source code quality

• Source code changes are understandable
• Variable and function names are meaningful
• Code comments are correct (logically and spelling)
• Required documentation changes are present and part of the PR
• bareos-check-sources --since-merge does not report any problems