ui: fix bug in the document download feature

[georgimld]

Checklist

• [ ] I have followed (at least) the PR section of the contributing guide.
• [ ] I fixed all necessary PR warnings
• [ ] The commit history is clean
• [ ] The E2E tests are passing
• [ ] If possible, the issue has been divided into more subtasks
• [ ] I did a self review before requesting a review from another team member

Description

The "document" tab in the "Workflowitem details" dialog was not displayed if the node didn't have its own storage service. This was a bug since the document can still be downloaded from other nodes or orgas.

• [x] Fix bug in UI
• [ ] Test with multiple orgas in deployments

Closes #1192

[github-actions[bot]]

	Warnings
:warning:	There were changes in the frontend, but no E2E-test was added or modified!

Generated by :no_entry_sign: dangerJS against 6850f6bd7f8af2b4a6f8a74c8a39f59d786448d3

[openkfwCI]

	Notes	Time
:white_check_mark:	Note for Reviewer: E2E tests on remote server succeeded	Tue, 06 Sep 2022 08:04:24 +0000

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