Data uploaded in preview mode is actually stored

[TjerkNan]

Describe the bug When uploading data in preview mode, the data should not actually be donated and stored in storage. When data is donated in preview mode and storage is visited, it is observed that a file is donated.

To Reproduce Steps to reproduce the behavior:

1. create data donation study
2. create storage (local)
3. Add data donation step in workflow with appropriate zip
4. Open preview
5. Donate data in preview
6. Go to storage card
7. Observe donated data in preview

Expected behavior No data to be stored when data donated in preview.

Screenshots

Desktop (please complete the following information):

• Safari

[mellelieuwes]

@TjerkNan this is by design. Creators can test everything before publish. This becomes more important when we introduce licenses.

Solution for possible confusion:

1. Creators can delete all files before publish. This feature will be implemented soon. See: #891
2. I will change the participant id to "preview" iso a real id so the files can always be recognized.

I will use this ticket to implement the second solution

[mellelieuwes]

When starting preview flow, the participant will be set "preview". This way the creator can always distinguish real donations from testing.

[TjerkNan]

Seems to work, I notice participant=preview