add backrest command label to all backrest-jobs to assist in backup j…

[jmccormick2001]

…ob cleanup

Checklist:

• [x ] Have you added an explanation of what your changes do and why you'd like them to be included?
• Have you updated or added documentation for the change, as applicable?
• [ x] Have you tested your changes on all related environments with successful results, as applicable?

Type of Changes:

• [x ] Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

What is the current behavior? (link to any open issues here)

backrest create stanza jobs were being removed as part of backup job cleanup, people typically would like to keep the stanza create job around for debugging.

What is the new behavior (if this is a feature change)?

a backrest-command label is added to backrest-job.json, this stores the backrest command being submitted, that label is now checked when deleting any prior backrest backup jobs.

Other information: