Fix deleting data priority in delete_workspace function

[alirezakv]

delete_workspace in Workspace.pm tries to delete data from other tables first but it will fail in line 161 when deleting runs. "runs" table has foreign keys for attachments, finding_changes and findings which will cause a failure here. Attachment table rows are not deleted in this function. finding_changes and findings are cleared after trying to clear runs table.

[MrSeccubus]

Have this on the roadmap for this quarter.