Use generated trace ID instead of empty one

Co-authored-by: tomer doron <[email protected]>

Author: StefanNienhuis

Sources/AWSLambdaRuntimeCore/ControlPlaneRequest.swift

@@ -54,7 +54,8 @@ struct Invocation: Hashable {
         self.requestID = requestID
         self.deadlineInMillisSinceEpoch = unixTimeInMilliseconds
         self.invokedFunctionARN = invokedFunctionARN
-        self.traceID = headers.first(name: AmazonHeaders.traceID) ?? ""
+        self.traceID = headers.first(name: AmazonHeaders.traceID) ?? 
+            "Root=\(AmazonHeaders.generateXRayTraceID());Sampled=0"
         self.clientContext = headers["Lambda-Runtime-Client-Context"].first
         self.cognitoIdentity = headers["Lambda-Runtime-Cognito-Identity"].first
     }