Improve template cleanup in ESRestTestCase (#70052)

Before this change upon wiping the cluster, we would get a list of all legacy and index component templates. For each template first attempt to delete it as legacy template if that returned a 404 then remove it as composable index template. In the worst case this means that we would make double the amount of delete requests for templates then is necessary.

This change first gets all composable index templates (if exist and if the cluster supports it) and then deletes these composable index templates. After this separately get a list of all legacy templates and then delete those legacy templates.

Relates to #69973

test/framework/src/main/java/org/elasticsearch/test/rest/ESRestTestCase.java

@@ -97,7 +97,6 @@ import static java.util.Collections.sort;
 import static java.util.Collections.unmodifiableList;
 import static org.hamcrest.Matchers.anEmptyMap;
 import static org.hamcrest.Matchers.anyOf;
-import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.everyItem;
 import static org.hamcrest.Matchers.in;
@@ -572,28 +571,26 @@ public abstract class ESRestTestCase extends ESTestCase {
                  * slows down the test because xpack will just recreate
                  * them.
                  */
-                Request request = new Request("GET", "_cat/templates");
-                request.addParameter("h", "name");
-                String templates = EntityUtils.toString(adminClient().performRequest(request).getEntity());
-                if (false == "".equals(templates)) {
-                    for (String template : templates.split("\n")) {
-                        if (isXPackTemplate(template)) continue;
-                        if ("".equals(template)) {
-                            throw new IllegalStateException("empty template in templates list:\n" + templates);
+                try {
+                    Request getTemplatesRequest = new Request("GET", "_index_template");
+                    Map<String, Object> composableIndexTemplates = XContentHelper.convertToMap(JsonXContent.jsonXContent,
+                        EntityUtils.toString(adminClient().performRequest(getTemplatesRequest).getEntity()), false);
+                    List<String> names = ((List<?>) composableIndexTemplates.get("index_templates")).stream()
+                        .map(ct -> (String) ((Map<?, ?>) ct).get("name"))
+                        .collect(Collectors.toList());
+                    for (String name : names) {
+                        if (isXPackTemplate(name)) {
+                            continue;
                         }
-                        logger.info("Clearing template [{}]", template);
                         try {
-                            adminClient().performRequest(new Request("DELETE", "_template/" + template));
+                            adminClient().performRequest(new Request("DELETE", "_index_template/" + name));
                         } catch (ResponseException e) {
-                            // This is fine, it could be a V2 template
-                            assertThat(e.getMessage(), containsString("index_template [" + template + "] missing"));
-                            try {
-                                adminClient().performRequest(new Request("DELETE", "_index_template/" + template));
-                            } catch (ResponseException e2) {
-                                // We hit a version of ES that doesn't support index templates v2 yet, so it's safe to ignore
-                            }
+                            logger.debug(new ParameterizedMessage("unable to remove index template {}", name), e);
                         }
                     }
+                } catch (Exception e) {
+                    logger.info("ignoring exception removing all composable index templates", e);
+                    // We hit a version of ES that doesn't support index templates v2 yet, so it's safe to ignore
                 }
                 try {
                     Request compReq = new Request("GET", "_component_template");
@@ -610,13 +607,26 @@ public abstract class ESRestTestCase extends ESTestCase {
                             }
                             adminClient().performRequest(new Request("DELETE", "_component_template/" + componentTemplate));
                         } catch (ResponseException e) {
-                                logger.debug(new ParameterizedMessage("unable to remove component template {}", componentTemplate), e);
+                            logger.debug(new ParameterizedMessage("unable to remove component template {}", componentTemplate), e);
                         }
                     }
                 } catch (Exception e) {
                     logger.info("ignoring exception removing all component templates", e);
                     // We hit a version of ES that doesn't support index templates v2 yet, so it's safe to ignore
                 }
+                Request getLegacyTemplatesRequest = new Request("GET", "_template");
+                Map<String, Object> legacyTemplates = XContentHelper.convertToMap(JsonXContent.jsonXContent,
+                    EntityUtils.toString(adminClient().performRequest(getLegacyTemplatesRequest).getEntity()), false);
+                for (String name : legacyTemplates.keySet()) {
+                    if (isXPackTemplate(name)) {
+                        continue;
+                    }
+                    try {
+                        adminClient().performRequest(new Request("DELETE", "_template/" + name));
+                    } catch (ResponseException e) {
+                        logger.debug(new ParameterizedMessage("unable to remove index template {}", name), e);
+                    }
+                }
             } else {
                 logger.debug("Clearing all templates");
                 adminClient().performRequest(new Request("DELETE", "_template/*"));