Pasting an image into a comment also uploads design
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### Summary
Pasting into a comment form on an issue also uploads a design.
### Steps to reproduce
1. Copy an image into the clipboard.
1. Paste it into a comment form using Ctrl-v
### What is the current *bug* behavior?
The image is both uploaded as an attachment and inserted into the Markdown, and also uploaded as a design.
### What is the expected *correct* behavior?
The image should only be added to the comment form.
### Output of checks
This bug happens on GitLab.com
### Possible fixes
issue