Fixed compile issues after cherry-pick

Note that the unit tests are still failing at this commit since the Lucene 9 libraries no longer hold constants for Lucene 7 and below, so the fromId logic resolves the Lucene version to 8.

Signed-off-by: Kartik Ganesh <gkart@amazon.com>

server/src/main/java/org/opensearch/cluster/metadata/IndexMetadata.java

@@ -37,6 +37,7 @@
 import com.carrotsearch.hppc.cursors.ObjectCursor;
 import com.carrotsearch.hppc.cursors.ObjectObjectCursor;
 import org.opensearch.Assertions;
+import org.opensearch.LegacyESVersion;
 import org.opensearch.Version;
 import org.opensearch.action.admin.indices.rollover.RolloverInfo;
 import org.opensearch.action.support.ActiveShardCount;

server/src/main/java/org/opensearch/common/lucene/Lucene.java

@@ -55,6 +55,7 @@
 import org.apache.lucene.index.SegmentCommitInfo;
 import org.apache.lucene.index.SegmentInfos;
 import org.apache.lucene.index.SegmentReader;
+import org.apache.lucene.index.StandardDirectoryReader;
 import org.apache.lucene.search.DocIdSetIterator;
 import org.apache.lucene.search.Explanation;
 import org.apache.lucene.search.FieldDoc;

server/src/main/java/org/opensearch/index/IndexSettings.java

@@ -590,7 +590,7 @@ public final class IndexSettings {
     private final String remoteStoreRepository;
     private final boolean isRemoteSnapshot;
     private Version extendedCompatibilitySnapshotVersion;
-    
+
     // volatile fields are updated via #updateIndexMetadata(IndexMetadata) under lock
     private volatile Settings settings;
     private volatile IndexMetadata indexMetadata;

server/src/main/java/org/opensearch/index/engine/ReadOnlyEngine.java

@@ -39,6 +39,7 @@
 import org.apache.lucene.search.ReferenceManager;
 import org.apache.lucene.store.Directory;
 import org.apache.lucene.store.Lock;
+import org.opensearch.Version;
 import org.opensearch.common.concurrent.GatedCloseable;
 import org.opensearch.common.lucene.Lucene;
 import org.opensearch.common.lucene.index.OpenSearchDirectoryReader;