How to mark a merge request as draft per default

We want to mark each merge reques as draft, automatically.
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The user should be able to remove the mark.
It looks like there is no setting for this feature.

As a workaround, I tried to run a pre-job (all other jobs “need” this job" which marks the MR as draft with a “/draft” comment. The MR is successfully marked as draft with this job, unfortunately it looks like this has no effect to the already scheduled pipeline.