Prevent additional API call when hostname not available

[Suthan Venkataramanaiah]

Recently, a Trove "list" API change was made (https://bugs.launchpad.net/trove/+bug/1339400) to return IPs or hostnames. That change allows Horizon or Trove CLI to show IPs or hostnames of instances in lists with no additional calls.

With the above change merged, exactly one of hostname or IP will always be present in the list of instances. However, a call per row is still possible in Horizon today if hostname is not present (but IP is). This is because Horizon checks for hostname first and since hostname is not present, it lazy-loads each instance which causes the slow rendering of Trove instances in Horizon.

One proposal is to allow clients of python-troveclient to disable lazy-loading of returned resources. Then Horizon would set the flag to disable lazy-loading when calling instances.list().

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/106843

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/108459

[OpenStack Infra (hudson-openstack)]

Change abandoned by Suthan Venkataramanaiah (<email address hidden>) on branch: master
Review: https://review.openstack.org/108459

[OpenStack Infra (hudson-openstack)]

Change abandoned by Suthan Venkataramanaiah (<email address hidden>) on branch: master
Review: https://review.openstack.org/106843
Reason: Abandoning in favor of a more generic solution

[Mat Lowery (mat-lowery)]

Adjusted bug description with a more generic solution.