Add 8.x backport index version

Author: jordan-powers

modules/mapper-extras/src/main/java/org/elasticsearch/index/mapper/extras/MatchOnlyTextFieldMapper.java

@@ -165,13 +165,21 @@ public MatchOnlyTextFieldMapper build(MapperBuilderContext context) {
         }
     }
 
+    private static boolean isSyntheticSourceStoredFieldInBinaryFormat(IndexVersion indexCreatedVersion) {
+        return indexCreatedVersion.onOrAfter(IndexVersions.MATCH_ONLY_TEXT_STORED_AS_BYTES)
+            || indexCreatedVersion.between(
+                IndexVersions.SYNTHETIC_SOURCE_STORE_ARRAYS_NATIVELY_BACKPORT_8_X,
+                IndexVersions.UPGRADE_TO_LUCENE_10_0_0
+            );
+    }
+
     public static final TypeParser PARSER = new TypeParser(
         (n, c) -> new Builder(
             n,
             c.indexVersionCreated(),
             c.getIndexAnalyzers(),
             c.isWithinMultiField(),
-            c.indexVersionCreated().onOrAfter(IndexVersions.MATCH_ONLY_TEXT_STORED_AS_BYTES)
+            isSyntheticSourceStoredFieldInBinaryFormat(c.indexVersionCreated())
         )
     );
 

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

@@ -145,6 +145,7 @@ private static Version parseUnchecked(String version) {
     public static final IndexVersion MAPPER_TEXT_MATCH_ONLY_MULTI_FIELDS_DEFAULT_NOT_STORED_8_19 = def(8_533_0_00, Version.LUCENE_9_12_1);
     public static final IndexVersion UPGRADE_TO_LUCENE_9_12_2 = def(8_534_0_00, Version.LUCENE_9_12_2);
     public static final IndexVersion SPARSE_VECTOR_PRUNING_INDEX_OPTIONS_SUPPORT_BACKPORT_8_X = def(8_535_0_00, Version.LUCENE_9_12_2);
+    public static final IndexVersion MATCH_ONLY_TEXT_STORED_AS_BYTES_BACKPORT_8_X = def(8_536_0_00, Version.LUCENE_9_12_2);
     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);