Admin-Compute-Instances dashboard shows "-" as image name for every
instance. Despite, Project-Compute-Instances dashboard displays image
name correctly. Admin dashboard just lacks code to resolve image name
Also, reverted commit deb55b8 which functionality is not needed anymore
Closes-Bug: #1932341
Change-Id: Ieb19e66dc51165d9935424b2e9ab5cdae757b07f