[Server][DBClientTest] Fix test data.
[Server][DBClientHatohol] Expand TriggerInfo to store hostgroup name.
[Server][FaceRest] Change a way to get hostgroup data from hatohol DB.

In the process,
- Add hostgroup id in trigger object.
- Remove the getHostgroupName function.
  -> Because I noticed unnecessary transaction ocuurs in this fucntion.
     So I change a way to get hostgroup name.