Port IndexVersions.UPGRADE_TO_LUCENE_9_12_2 to main (elastic#129832)

This commit ports the IndexVersions.UPGRADE_TO_LUCENE_9_12_2 constant to the main branch.

This is required after the update of Lucene 9.12.2 in the 8.19 branch, see elastic#129555.

Author: ChrisHegarty

muted-tests.yml

@@ -574,9 +574,6 @@ tests:
 - class: org.elasticsearch.search.query.RescoreKnnVectorQueryIT
   method: testKnnRetriever
   issue: https://github.com/elastic/elasticsearch/issues/129818
-- class: org.elasticsearch.qa.verify_version_constants.VerifyVersionConstantsIT
-  method: testLuceneVersionConstant
-  issue: https://github.com/elastic/elasticsearch/issues/125638
 - class: org.elasticsearch.xpack.esql.qa.single_node.GenerativeIT
   method: test
   issue: https://github.com/elastic/elasticsearch/issues/129819

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

@@ -143,6 +143,7 @@ private static Version parseUnchecked(String version) {
     public static final IndexVersion SEMANTIC_TEXT_DEFAULTS_TO_BBQ_BACKPORT_8_X = def(8_531_0_00, Version.LUCENE_9_12_1);
     public static final IndexVersion INDEX_INT_SORT_INT_TYPE_8_19 = def(8_532_0_00, Version.LUCENE_9_12_1);
     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 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);