feat: support optional otel global initialization for #3284 (#3292)

core/trace/agent.go

@@ -33,6 +33,11 @@ var (
 
 // StartAgent starts an opentelemetry agent.
 func StartAgent(c Config) {
+
+	if c.Disabled {
+		return
+	}
+
 	lock.Lock()
 	defer lock.Unlock()