Retry preview loading on 425 status code

[JammingBen]

Describe the bug

Requests for preview images that are in post-processing and return a 425 status code never get retried. As a result, the images will never appear in such case until the user reloads the page.

Steps to reproduce

1. Set POSTPROCESSING_DELAY=5s in oCIS
2. Open a space
3. Upload a space image

Expected behavior

The space image is being fetched at some point after the post-processing is finished

Actual behavior

The space image is never loaded.