Exclude tmp dirs from backups

What does this MR do?

Add '--exclude' for tmp directories in located in paths included in backups. Currently a backup job may fail due to a file or directory within a tmp dir being removed during the backup.

This change adds a new 'exclude' optional parameter to Backup::Files to indicate directories that should not be included in backups. This should prevent changes in temporary files from breaking backups and also stop unneeded files from being included in the backup archive.

Related to #244397 (closed)

Does this MR meet the acceptance criteria?

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