Revert "Disable concurrent search for filter duplicates"

CHANGELOG.md

@@ -30,7 +30,6 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 - Use env variable (OPENSEARCH_FIPS_MODE) to enable opensearch to run in FIPS enforced mode instead of checking for existence of bcFIPS jars ([#20625](https://github.com/opensearch-project/OpenSearch/pull/20625))
 - Update streaming flag to use search request context ([#20530](https://github.com/opensearch-project/OpenSearch/pull/20530))
 - Move pull-based ingestion classes from experimental to publicAPI ([#20704](https://github.com/opensearch-project/OpenSearch/pull/20704))
-- Disable concurrent search for filter duplicates in significant_text ([#20857](https://github.com/opensearch-project/OpenSearch/pull/20857))
 
 ### Fixed
 - Relax index template pattern overlap check to use minimum-string heuristic, allowing distinguishable multi-wildcard patterns at the same priority ([#20702](https://github.com/opensearch-project/OpenSearch/pull/20702))

server/src/main/java/org/opensearch/search/aggregations/bucket/terms/SignificantTextAggregatorFactory.java

@@ -315,9 +315,6 @@ public void close() {
 
     @Override
     protected boolean supportsConcurrentSegmentSearch() {
-        // The underlying structured used to find duplicate byte sequences (DuplicateByteSequenceSpotter)
-        // is stateful and not thread-safe, so disable concurrent search if this particular feature is
-        // being used.
-        return filterDuplicateText == false;
+        return true;
     }
 }