Advance ords when tryReadAHead and there is only one term. (elastic#141576)

Closes elastic#141529

Author: martijnvg

muted-tests.yml

@@ -327,9 +327,9 @@ tests:
 - class: org.elasticsearch.search.query.VectorIT
   method: testFilteredQueryStrategy
   issue: https://github.com/elastic/elasticsearch/issues/141469
-- class: org.elasticsearch.index.codec.tsdb.es819.ES819TSDBDocValuesFormatTests
-  method: testOptionalColumnAtATimeReader
-  issue: https://github.com/elastic/elasticsearch/issues/141529
+- class: org.elasticsearch.xpack.security.authc.TokenServiceTests
+  method: testAttachAndGetToken
+  issue: https://github.com/elastic/elasticsearch/issues/141470
 - class: org.elasticsearch.indices.recovery.IndexRecoveryIT
   method: testSourceThrottling
   issue: https://github.com/elastic/elasticsearch/issues/141548

server/src/main/java/org/elasticsearch/index/codec/tsdb/es819/ES819TSDBDocValuesProducer.java

@@ -984,6 +984,8 @@ public BlockLoader.Block tryRead(
             BlockLoader.Block tryReadAHead(BlockLoader.BlockFactory factory, BlockLoader.Docs docs, int offset) throws IOException {
                 if (ords instanceof BaseDenseNumericValues denseOrds) {
                     if (entry.termsDictEntry.termsDictSize == 1) {
+                        int lastDoc = docs.get(docs.count() - 1);
+                        denseOrds.advanceExact(lastDoc);
                         return factory.constantBytes(BytesRef.deepCopyOf(lookupOrd(0)), docs.count() - offset);
                     }
                     if (valuesSorted == false) {