Description of problem:
When requesting disk snapshots of a disk (ovirt-engine/api/disks/{diskid}/disksnapshots or ovirt-engine/api/disks/{diskid}/disksnapshots/{snapshotid}), the 'parent' element holds incorrect href - disk href instead of the disksnapshot href.

Version-Release number of selected component (if applicable):


How reproducible:
100%

Steps to Reproduce:
1. Create at least one disk snapshot
2. Issue REST API request ovirt-engine/api/disks/{diskid}/disksnapshots?include_active&include_template or ovirt-engine/api/disks/{diskid}/disksnapshots/{snapshotid}

Actual results:
On disk snapshots that have the <parent> element, the href attribute will be like this:
<parent href="/ovirt-engine/api/disks/71b3d7c7-19ee-4b14-adb5-17422e1e7407" id="af16f154-f973-46ee-9683-5c456e3cb51e"/>

Expected results:
<parent href="/ovirt-engine/api/disks/71b3d7c7-19ee-4b14-adb5-17422e1e7407/disksnapshots/af16f154-f973-46ee-9683-5c456e3cb51e" id="af16f154-f973-46ee-9683-5c456e3cb51e"/>

Additional info:
Note that when 'include_template' flag is requested, and one of the disk_snapshots have a template disk as a parent (as described here https://bugzilla.redhat.com/1900597) - this template disk snapshot belongs to another disk, thus the href should be built accordingly.