Docs: correct indentation on callout

I've aligned them all to 70 characters except this one....

Relates to #24354

client/rest-high-level/src/test/java/org/elasticsearch/client/documentation/QueryDSLDocumentationTests.java

@@ -134,7 +134,7 @@ public class QueryDSLDocumentationTests extends ESTestCase {
 
     public void testExists() {
         // tag::exists
-        existsQuery("name");   // <1>
+        existsQuery("name");                                         // <1>
         // end::exists
     }