[apiserver] deduplicate proxy replica status writes on xDS events

The event-driven path blindly appended replicas without checking for
duplicates and always called Status().Update() even when nothing changed.
This caused unnecessary resourceVersion bumps that triggered downstream
reconciliation churn.

Add duplicate detection before append and skip the write when no change
occurred, matching the pattern already used by the 1-minute resync timer.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: dilyevsky

pkg/apiserver/controllers/proxy.go

@@ -224,23 +224,38 @@ func (r *ProxyReconciler) run(ctx context.Context) {
 					continue
 				}
 
+				updated := false
 				if !update.Delete {
-					p.Status.Replicas = append(p.Status.Replicas, &corev1alpha2.ProxyReplicaStatus{
-						Name:        meta.Name,
-						ConnectedAt: meta.ConnectedAt,
-						Addresses:   nodeMetadataToAddresses(meta),
-					})
+					// Check if replica already exists before appending.
+					found := false
+					for _, replica := range p.Status.Replicas {
+						if replica.Name == meta.Name {
+							found = true
+							break
+						}
+					}
+					if !found {
+						p.Status.Replicas = append(p.Status.Replicas, &corev1alpha2.ProxyReplicaStatus{
+							Name:        meta.Name,
+							ConnectedAt: meta.ConnectedAt,
+							Addresses:   nodeMetadataToAddresses(meta),
+						})
+						updated = true
+					}
 				} else {
 					for i, replica := range p.Status.Replicas {
 						if replica.Name == meta.Name {
 							p.Status.Replicas = append(p.Status.Replicas[:i], p.Status.Replicas[i+1:]...)
+							updated = true
 							break
 						}
 					}
 				}
 
-				if err := r.Status().Update(ctx, p); err != nil {
-					slog.Error("Failed to update proxy status", "proxy", proxyName, "error", err)
+				if updated {
+					if err := r.Status().Update(ctx, p); err != nil {
+						slog.Error("Failed to update proxy status", "proxy", proxyName, "error", err)
+					}
 				}
 			}