Rename AZP_USENEWNODEHANDLERTELEMETRY knob (#4878)

* Update AgentKnobs.cs

* Update AgentKnobs.cs

Author: kirill-ivlev

src/Agent.Sdk/Knob/AgentKnobs.cs

@@ -569,8 +569,7 @@ public class AgentKnobs
         public static readonly Knob UseNewNodeHandlerTelemetry = new Knob(
             nameof(UseNewNodeHandlerTelemetry),
             "Enables new approach to publish node handler information to the telemetry",
-            new RuntimeKnobSource("AZP_USENEWNODEHANDLERTELEMETRY"),
-            new EnvironmentKnobSource("AZP_USENEWNODEHANDLERTELEMETRY"),
+            new PipelineFeatureSource("USENEWNODEHANDLERTELEMETRY"),
             new BuiltInDefaultKnobSource("false"));
 
         public static readonly Knob ProcessHandlerEnableNewLogic = new Knob(