Customer observed that dashboard is loading really slow when many drafts are fetched.

Steps to reproduce:
1. Create many drafts (> 5000).
2. Log in to the BO.

Result:
Dashboard is loading really slow.

Additional information:
In the attachment, there is an excerpt of the example query which takes much time to execute. The bigger amount of drafts is created, the bigger final query is generated.
It is initialized while creating "Me->Drafts" tab.
ref: https://github.com/ezsystems/ezplatform-admin-ui/blob/1.4/src/lib/UI/Dataset/ContentDraftsDataset.php#L57
The final query is generated here:
https://github.com/ezsystems/ezpublish-kernel/blob/7.4/eZ/Publish/Core/Persistence/Legacy/Content/Gateway/DoctrineDatabase.php#L2032