Rename offset encoding 8.x backport version (#125447)

Renamed to SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_BACKPORT_8_X since it
will include all 8.x implementations of arrays offset encoding.

server/src/main/java/org/elasticsearch/index/IndexVersions.java

@@ -136,7 +136,7 @@ public class IndexVersions {
     public static final IndexVersion INFERENCE_METADATA_FIELDS_BACKPORT = def(8_524_0_00, parseUnchecked("9.12.1"));
     public static final IndexVersion LOGSB_OPTIONAL_SORTING_ON_HOST_NAME_BACKPORT = def(8_525_0_00, parseUnchecked("9.12.1"));
     public static final IndexVersion USE_SYNTHETIC_SOURCE_FOR_RECOVERY_BY_DEFAULT_BACKPORT = def(8_526_0_00, parseUnchecked("9.12.1"));
-    public static final IndexVersion SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_KEYWORD_BACKPORT_8_X = def(8_527_0_00, Version.LUCENE_9_12_1);
+    public static final IndexVersion SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_BACKPORT_8_X = def(8_527_0_00, Version.LUCENE_9_12_1);
     public static final IndexVersion UPGRADE_TO_LUCENE_10_0_0 = def(9_000_0_00, Version.LUCENE_10_0_0);
     public static final IndexVersion LOGSDB_DEFAULT_IGNORE_DYNAMIC_BEYOND_LIMIT = def(9_001_0_00, Version.LUCENE_10_0_0);
     public static final IndexVersion TIME_BASED_K_ORDERED_DOC_ID = def(9_002_0_00, Version.LUCENE_10_0_0);

server/src/main/java/org/elasticsearch/index/mapper/FieldArrayContext.java

@@ -119,7 +119,7 @@ public class FieldArrayContext {
     ) {
         return indexCreatedVersion.onOrAfter(minSupportedVersionMain)
             || indexCreatedVersion.between(
-                IndexVersions.SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_KEYWORD_BACKPORT_8_X,
+                IndexVersions.SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_BACKPORT_8_X,
                 IndexVersions.UPGRADE_TO_LUCENE_10_0_0
             );
     }