Revert "@timestamp handling from opsgenie#165 (#92)" (#102)

This reverts commit c572daa.

pkg/kube/event.go

@@ -12,7 +12,6 @@ type EnhancedEvent struct {
 	corev1.Event   `json:",inline"`
 	ClusterName    string                  `json:"clusterName"`
 	InvolvedObject EnhancedObjectReference `json:"involvedObject"`
-	Timestamp      time.Time               `json:"@timestamp"`
 }
 
 // DeDot replaces all dots in the labels and annotations with underscores. This is required for example in the
@@ -48,7 +47,6 @@ type EnhancedObjectReference struct {
 // ToJSON does not return an error because we are %99 confident it is JSON serializable.
 // TODO(makin) Is it a bad practice? It's open to discussion.
 func (e *EnhancedEvent) ToJSON() []byte {
-	e.Timestamp = e.FirstTimestamp.Time
 	b, _ := json.Marshal(e)
 	return b
 }