fix(provider): fix the content returned by sayHello interface

- Removed environment variable acquisition logic
- Modify the return value to the request parameter name

demo/demo-etcd/provider/src/main/java/org/apache/servicecomb/samples/ProviderController.java

@@ -38,7 +38,8 @@ public void setEnvironment(Environment environment) {
   // a very simple service to echo the request parameter
   @GetMapping("/sayHello")
   public String sayHello(@RequestParam("name") String name) {
-    return "Hello " + environment.getProperty("servicecomb.rest.address");
+//    return "Hello " + environment.getProperty("servicecomb.rest.address");
+    return "Hello " + name;
   }
 
   @GetMapping("/getConfig")