core: add missing engine lock in run once

RunVmOnce should take the engine lock that RunVm takes, but it didn't
take locks at all because the LockIdNameAttribute annotation was
missing. Thus, the LockIdNameAttribute annotation is added to RunVmOnce.

Change-Id: Iff7c176ad3741b501df4ce7fab08b89c11a33be2
Bug-Url: https://bugzilla.redhat.com/1071997
Signed-off-by: Arik Hadas <ahadas@redhat.com>