Print out state of index if didn't recover from the snapshot (elastic…

…#106726)

Add additional debug information about the index and its recovery state
if the assertion for `recoveredFromSnapshotBytes` fails

See elastic#87568

x-pack/plugin/snapshot-based-recoveries/src/internalClusterTest/java/org/elasticsearch/xpack/snapshotbasedrecoveries/recovery/SnapshotBasedIndexRecoveryIT.java

@@ -986,7 +986,11 @@ public void testRecoveryConcurrentlyWithIndexing() throws Exception {
         if (waitForSnapshotDownloadToStart) {
             // must complete using snapshots alone.
             RecoveryState recoveryState = getLatestPeerRecoveryStateForShard(indexName, 0);
-            assertThat(recoveryState.getIndex().recoveredFromSnapshotBytes(), equalTo(snapshotSizeForIndex));
+            assertThat(
+                "Index " + recoveryState.getIndex() + " should be completely recovered from the snapshot",
+                recoveryState.getIndex().recoveredFromSnapshotBytes(),
+                equalTo(snapshotSizeForIndex)
+            );
         }
 
         assertDocumentsAreEqual(indexName, numDocs.get());