Hi,
While this might have fit your needs in the past, it is not a recommended solution for correcting /usr space size issues to symlink that partition. It would be preferred to repartition to have more space available and use the recommended size partitions that cPanel recommends for installation.
At this point, I'm going to go ahead and close out the thread. If there are any further questions in regards to /usr size, please open up a technical support ticket in WHM > Support Center > Contact cPanel or using the link in my signature.
Thanks!