[fix-35290][core] fix watermark metrics throw a warning log

Author: a49a

core/src/main/java/com/dtstack/flink/sql/watermarker/AbstractCustomerWaterMarker.java

@@ -92,7 +92,6 @@ public IterationRuntimeContext getIterationRuntimeContext() {
     public void setRuntimeContext(RuntimeContext t) {
         this.runtimeContext = t;
         eventDelayGauge = new EventDelayGauge();
-        t.getMetricGroup().getAllVariables().put("<source_tag>", fromSourceTag);
         t.getMetricGroup().gauge(MetricConstant.DT_EVENT_DELAY_GAUGE, eventDelayGauge);
     }