Re-add semantic_text.inner_hits cluster feature (#114180)

Re-add the `semantic_text.inner_hits` cluster feature to fix serverless
test failures

Author: Mikep86

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/InferenceFeatures.java

@@ -10,6 +10,7 @@
 import org.elasticsearch.features.FeatureSpecification;
 import org.elasticsearch.features.NodeFeature;
 import org.elasticsearch.xpack.inference.mapper.SemanticTextFieldMapper;
+import org.elasticsearch.xpack.inference.queries.SemanticQueryBuilder;
 import org.elasticsearch.xpack.inference.rank.random.RandomRankRetrieverBuilder;
 import org.elasticsearch.xpack.inference.rank.textsimilarity.TextSimilarityRankRetrieverBuilder;
 
@@ -25,7 +26,8 @@ public Set<NodeFeature> getFeatures() {
         return Set.of(
             TextSimilarityRankRetrieverBuilder.TEXT_SIMILARITY_RERANKER_RETRIEVER_SUPPORTED,
             RandomRankRetrieverBuilder.RANDOM_RERANKER_RETRIEVER_SUPPORTED,
-            SemanticTextFieldMapper.SEMANTIC_TEXT_SEARCH_INFERENCE_ID
+            SemanticTextFieldMapper.SEMANTIC_TEXT_SEARCH_INFERENCE_ID,
+            SemanticQueryBuilder.SEMANTIC_TEXT_INNER_HITS
         );
     }
 

x-pack/plugin/inference/src/main/java/org/elasticsearch/xpack/inference/queries/SemanticQueryBuilder.java

@@ -16,6 +16,7 @@
 import org.elasticsearch.cluster.metadata.InferenceFieldMetadata;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
+import org.elasticsearch.features.NodeFeature;
 import org.elasticsearch.index.mapper.MappedFieldType;
 import org.elasticsearch.index.query.AbstractQueryBuilder;
 import org.elasticsearch.index.query.MatchNoneQueryBuilder;
@@ -49,6 +50,9 @@
 import static org.elasticsearch.xpack.core.ClientHelper.executeAsyncWithOrigin;
 
 public class SemanticQueryBuilder extends AbstractQueryBuilder<SemanticQueryBuilder> {
+    // **** THE semantic_text.inner_hits CLUSTER FEATURE IS DEFUNCT, NEVER USE IT ****
+    public static final NodeFeature SEMANTIC_TEXT_INNER_HITS = new NodeFeature("semantic_text.inner_hits");
+
     public static final String NAME = "semantic";
 
     private static final ParseField FIELD_FIELD = new ParseField("field");