[TEST] wait for yellow after setup doc tests (#18726)

* [TEST] wait for yellow after setup doc tests

We have many places in the doc where we expect and index to be
yellow before we execute a query. Therefore we have to
always wait for yellow after setup.

buildSrc/src/main/groovy/org/elasticsearch/gradle/doc/RestTestsFromSnippetsTask.groovy

@@ -170,6 +170,13 @@ public class RestTestsFromSnippetsTask extends SnippetsTask {
             current.println('---')
             current.println("setup:")
             body(setup)
+            // always wait for yellow before anything is executed
+            current.println(
+                    "  - do:\n" +
+                    "      raw:\n" +
+                    "        method: GET\n" +
+                    "        path: \"_cluster/health\"\n" +
+                    "        wait_for_status: \"yellow\"")
         }
 
         private void body(Snippet snippet) {

docs/reference/query-dsl/nested-query.asciidoc

@@ -23,7 +23,6 @@ PUT /my_index
     }
 }
 
-GET _cluster/health?wait_for_status=yellow
 --------------------------------------------------
 // CONSOLE
 // TESTSETUP

docs/reference/query-dsl/parent-id-query.asciidoc

@@ -29,7 +29,6 @@ PUT /my_index
     }
 }
 
-GET /_cluster/health?wait_for_status=yellow
 ------------------------------------------
 // CONSOLE
 // TESTSETUP