Add more logging for IndexRecoveryIT#testSourceThrottling (#122830)

I couldn't reproduce the failure of the throttling time being zero on
the recovery target node. Added more logging for the stats in case of
failure.

Resolve #122712

Author: arteam

muted-tests.yml

@@ -318,9 +318,6 @@ tests:
 - class: org.elasticsearch.search.basic.SearchWithRandomDisconnectsIT
   method: testSearchWithRandomDisconnects
   issue: https://github.com/elastic/elasticsearch/issues/122707
-- class: org.elasticsearch.indices.recovery.IndexRecoveryIT
-  method: testSourceThrottling
-  issue: https://github.com/elastic/elasticsearch/issues/122712
 - class: org.elasticsearch.xpack.esql.action.EsqlActionBreakerIT
   issue: https://github.com/elastic/elasticsearch/issues/122810
 - class: org.elasticsearch.snapshots.DedicatedClusterSnapshotRestoreIT

server/src/internalClusterTest/java/org/elasticsearch/indices/recovery/IndexRecoveryIT.java

@@ -342,9 +342,17 @@ public void assertNodeHasThrottleTimeAndNoRecoveries(String nodeName, Boolean is
         assertThat(recoveryStats.currentAsSource(), equalTo(0));
         assertThat(recoveryStats.currentAsTarget(), equalTo(0));
         if (isRecoveryThrottlingNode) {
-            assertThat("Throttling should be >0 for '" + nodeName + "'", recoveryStats.throttleTime().millis(), greaterThan(0L));
+            assertThat(
+                "Throttling should be >0 for '" + nodeName + "'. Node stats: " + nodesStatsResponse,
+                recoveryStats.throttleTime().millis(),
+                greaterThan(0L)
+            );
         } else {
-            assertThat("Throttling should be =0 for '" + nodeName + "'", recoveryStats.throttleTime().millis(), equalTo(0L));
+            assertThat(
+                "Throttling should be =0 for '" + nodeName + "'. Node stats: " + nodesStatsResponse,
+                recoveryStats.throttleTime().millis(),
+                equalTo(0L)
+            );
         }
     }