Do not check for domain liveness in virDomainObjSetDefTransient

Do not check for domain liveness in virDomainObjSetDefTransient

Remove the live attribute and mark the definition as transient
whether the domain is runing or not.

There were only two callers left calling with live=false:
* testDomainStartState, where the domain already is active
  because we assigned vm->def->id just a few lines above the call
* virDomainObjGetPersistentDef, which now only calls
  virDomainObjSetDefTransient for an active domain