Broken attachment links in comments

Quoting @anonym-guest:

See e.g. https://gitlab.tails.boum.org/tails/tails/-/issues/17367

The attachment links in the Attachment section work fine. However, the links in the comments where they were added have bad URLs:

https://redmine.tails.boum.org/code/attachments/download/2547/GNOME+Settings+Selection.png

It should be:

https://redmine.tails.boum.org/code/attachments/download/2547/GNOME%20Settings%20Selection.png