Viewing a configuration's details in the worker results deletion modal shows a placeholder

Found while working on !1913 (merged)

1. Browse to any project that has any worker result from a WorkerRun with a WorkerConfiguration assigned to it, with admin access.
2. Open Process → Delete worker results.
3. In the table of CorpusWorkerVersion, click on the name of any WorkerConfiguration.
4. The worker configuration modal opens with a placeholder intended for the selection mode, not the read-only display:
   
5. Cry.