Fix an issue with ConduitQueryConduitAPIMethod

Fixes an issue with D9991. A user was hitting the following exception:

```
echo '{}' | arc --conduit-uri='http://phabricator.joshuaspence.com'
call-conduit conduit.query
Waiting for JSON parameters on stdin...
Exception
[HTTP/500] Internal Server Error
>>> UNRECOVERABLE FATAL ERROR <<<

Call to a member function getAPIMethodName() on a non-object

/usr/src/phabricator/src/applications/conduit/method/ConduitQueryConduitAPIMethod.php:34

┻━┻ ︵ ¯\_(ツ)_/¯ ︵ ┻━┻
(Run with --trace for a full exception trace.)
```

Auditors: epriestley

src/applications/conduit/method/ConduitQueryConduitAPIMethod.php

@@ -27,15 +27,15 @@ final class ConduitQueryConduitAPIMethod extends ConduitAPIMethod {
       ->setAncestorClass('ConduitAPIMethod')
       ->setType('class')
       ->setConcreteOnly(true)
-      ->selectSymbolsWithoutLoading();
+      ->loadObjects();
 
     $names_to_params = array();
     foreach ($classes as $class) {
-      $method_name = $class['name'];
-      $obj = newv($method_name, array());
-      $names_to_params[$this->getAPIMethodNameFromClassName($method_name)] =
-        array('params' => $obj->defineParamTypes());
+      $names_to_params[$class->getAPIMethodName()] = array(
+        'params' => $class->defineParamTypes(),
+      );
     }
+
     return $names_to_params;
   }