Add logging to FullClusterRestartSystemIndexCompatibilityIT

This test occasionally fails on version 8.19 clusters when we are
waiting for system index migration to finish. In order to understand
this better, log time when migration API call is sent and also catch
assertion error and log migration API status in that case to help the
investigation.

Author: cbuescher

qa/lucene-index-compatibility/src/javaRestTest/java/org/elasticsearch/lucene/FullClusterRestartSystemIndexCompatibilityIT.java

@@ -9,6 +9,7 @@
 
 package org.elasticsearch.lucene;
 
+import org.apache.http.util.EntityUtils;
 import org.elasticsearch.client.Request;
 import org.elasticsearch.client.RequestOptions;
 import org.elasticsearch.client.Response;
@@ -17,6 +18,7 @@
 import org.elasticsearch.cluster.metadata.IndexMetadata;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.test.cluster.util.Version;
+import org.elasticsearch.test.junit.annotations.TestIssueLogging;
 import org.elasticsearch.test.rest.ObjectPath;
 
 import java.io.IOException;
@@ -43,6 +45,10 @@ public FullClusterRestartSystemIndexCompatibilityIT(Version version) {
      * 2. After update to N-1 (latest) perform a system index migration step, also write block the index
      * 3. on N, check that async search results are still retrievable and we can write to the system index
      */
+    @TestIssueLogging(
+        value = "org.elasticsearch.lucene.FullClusterRestartSystemIndexCompatibilityIT:DEBUG",
+        issueUrl = "https://github.com/elastic/elasticsearch/issues/127245"
+    )
     public void testAsyncSearchIndexMigration() throws Exception {
         final String index = suffix("index");
         final String asyncSearchIndex = ".async-search";
@@ -83,19 +89,29 @@ public void testAsyncSearchIndexMigration() throws Exception {
                 ObjectPath.createFromResponse(client().performRequest(migrateRequest)).evaluate("features.0.feature_name"),
                 equalTo("async_search")
             );
-            assertBusy(() -> {
-                Request checkMigrateProgress = new Request("GET", "/_migration/system_features");
-                Response resp = null;
-                try {
-                    assertFalse(
-                        ObjectPath.createFromResponse(client().performRequest(checkMigrateProgress))
-                            .evaluate("migration_status")
-                            .equals("IN_PROGRESS")
-                    );
-                } catch (IOException e) {
-                    throw new AssertionError("System feature migration failed", e);
-                }
-            });
+
+            logger.debug("--> starting system index migration");
+            Request checkMigrateProgress = new Request("GET", "/_migration/system_features");
+            try {
+                assertBusy(() -> {
+                    Response resp = null;
+                    try {
+                        assertFalse(
+                            ObjectPath.createFromResponse(client().performRequest(checkMigrateProgress))
+                                .evaluate("migration_status")
+                                .equals("IN_PROGRESS")
+                        );
+                    } catch (IOException e) {
+                        throw new AssertionError("System feature migration failed", e);
+                    }
+                });
+            } catch (AssertionError e) {
+                logger.debug(
+                    "--> system index migration not finished yet, response: {}",
+                    EntityUtils.toString(client().performRequest(checkMigrateProgress).getEntity())
+                );
+                throw e;
+            }
 
             // check search results from n-2 search are still readable
             assertAsyncSearchHitCount(async_search_ids.get("n-2_id"), numDocs);