Create datacube for xcombelle on devserver role

Summary:
Similar to home directories, this configuration allows:

• ZFS auto snapshots
• user permissions on ZFS datasets

Ref T1537

Test Plan:
Deploy on WindRiver, then:

• ls -lh /datacube
• check snapshot is created after 5 minutes

Reviewers: dereckson

Reviewed By: dereckson

Subscribers: xcombelle

Maniphest Tasks: T1537

Differential Revision: https://devcentral.nasqueron.org/D3088