fix: delegate peer tagging to BaseDecorator for IPv6 and config support

Use DECORATE.onPeerConnection() and setPeerPort() instead of manually
setting peer tags. This correctly classifies IPv6 addresses as peer.ipv6
(instead of forcing peer.ipv4) and honors the trace.peer.hostname.enabled
config toggle for peer.hostname.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: bm1549

dd-java-agent/instrumentation/synapse-3.0/src/main/java/datadog/trace/instrumentation/synapse3/SynapseClientInstrumentation.java

@@ -22,7 +22,6 @@
 import datadog.trace.agent.tooling.InstrumenterModule;
 import datadog.trace.agent.tooling.annotation.AppliesOn;
 import datadog.trace.bootstrap.instrumentation.api.AgentSpan;
-import datadog.trace.bootstrap.instrumentation.api.Tags;
 import net.bytebuddy.asm.Advice;
 import org.apache.axis2.context.MessageContext;
 import org.apache.http.HttpInetConnection;
@@ -110,17 +109,11 @@ public static void requestSubmitted(
       AgentSpan span = spanFromContext(scope.context());
       DECORATE.onRequest(span, TargetContext.getRequest(connection).getRequest());
 
-      // set peer hostname from the connection since request URIs are relative paths
+      // set peer info from the connection since request URIs are relative paths
       if (connection instanceof HttpInetConnection) {
-        java.net.InetAddress remoteAddress = ((HttpInetConnection) connection).getRemoteAddress();
-        if (remoteAddress != null) {
-          span.setTag(Tags.PEER_HOSTNAME, remoteAddress.getHostName());
-          span.setTag(Tags.PEER_HOST_IPV4, remoteAddress.getHostAddress());
-          int remotePort = ((HttpInetConnection) connection).getRemotePort();
-          if (remotePort > 0) {
-            span.setTag(Tags.PEER_PORT, remotePort);
-          }
-        }
+        HttpInetConnection inetConn = (HttpInetConnection) connection;
+        DECORATE.onPeerConnection(span, inetConn.getRemoteAddress());
+        DECORATE.setPeerPort(span, inetConn.getRemotePort());
       }
       scope.close();
     }