Add scaleUp stabilization window to mitigate metric oscillation

AverageValue divides total token throughput by replica count, which means
the per-replica value halves after a scale-up event. With stabilizationWindowSeconds: 0
this could cause flapping near the threshold. Setting it to 30s requires the
metric to stay above threshold for two consecutive polling intervals before
a scale-up is committed, while the existing 120s scaleDown window prevents
premature scale-down.

Author: tmvfb

serving/kserve-keda-autoscaling/scaled-object.yaml

@@ -26,7 +26,7 @@ spec:
     horizontalPodAutoscalerConfig:
       behavior:
         scaleUp:
-          stabilizationWindowSeconds: 0
+          stabilizationWindowSeconds: 30  # short window to absorb metric noise before committing to scale-up
         scaleDown:
           stabilizationWindowSeconds: 120
           policies: