Fix compilation issue for PR #17535 during backport

Signed-off-by: Ashish Singh <ssashish@amazon.com>

Author: ashking94

server/src/internalClusterTest/java/org/opensearch/remotestore/RemoteStoreStatsIT.java

@@ -283,12 +283,12 @@ public void testDownloadStatsCorrectnessSinglePrimarySingleReplica() throws Exce
                 // Existing validation logic
                 List<RemoteStoreStats> primaryStatsList = Arrays.stream(response.getRemoteStoreStats())
                     .filter(remoteStoreStats -> remoteStoreStats.getShardRouting().primary())
-                    .toList();
+                    .collect(Collectors.toList());
                 assertEquals(1, primaryStatsList.size());
 
                 List<RemoteStoreStats> replicaStatsList = Arrays.stream(response.getRemoteStoreStats())
                     .filter(remoteStoreStats -> !remoteStoreStats.getShardRouting().primary())
-                    .toList();
+                    .collect(Collectors.toList());
                 assertEquals(1, replicaStatsList.size());
 
                 RemoteSegmentTransferTracker.Stats primaryStats = primaryStatsList.getFirst().getSegmentStats();
@@ -401,7 +401,7 @@ private void validateZeroStatePrimaryStats(RemoteSegmentTransferTracker.Stats pr
     private void validateZeroStateReplicaStats(RemoteStoreStatsResponse zeroStateResponse, boolean multipleShardsExpected) {
         List<RemoteStoreStats> zeroStateReplicaStats = Arrays.stream(zeroStateResponse.getRemoteStoreStats())
             .filter(remoteStoreStats -> !remoteStoreStats.getShardRouting().primary())
-            .toList();
+            .collect(Collectors.toList());
 
         if (multipleShardsExpected) {
             zeroStateReplicaStats.forEach(stats -> {
@@ -434,8 +434,8 @@ private SetOnce<RemoteSegmentTransferTracker.Stats> prepareZeroStateStats(
 
             RemoteSegmentTransferTracker.Stats primaryStats = Arrays.stream(zeroStateResponse.getRemoteStoreStats())
                 .filter(remoteStoreStats -> remoteStoreStats.getShardRouting().primary())
-                .toList()
-                .getFirst()
+                .collect(Collectors.toList())
+                .get(0)
                 .getSegmentStats();
 
             validateZeroStatePrimaryStats(primaryStats);