Revert "Adds unused lower level ivf knn query (#127852)" (#128003)

This reverts commit a7a430f.

Author: john-wagster

server/src/main/java/org/elasticsearch/index/codec/vectors/IVFVectorsFormat.java

@@ -46,7 +46,7 @@
  */
 public class IVFVectorsFormat extends KnnVectorsFormat {
 
-    public static final FeatureFlag IVF_FORMAT_FEATURE_FLAG = new FeatureFlag("ivf_format");
+    static final FeatureFlag IVF_FORMAT_FEATURE_FLAG = new FeatureFlag("ivf_format");
     public static final String IVF_VECTOR_COMPONENT = "IVF";
     public static final String NAME = "IVFVectorsFormat";
     // centroid ordinals -> centroid values, offsets

server/src/main/java/org/elasticsearch/index/codec/vectors/IVFVectorsReader.java

@@ -32,7 +32,6 @@
 import org.apache.lucene.util.FixedBitSet;
 import org.apache.lucene.util.hnsw.NeighborQueue;
 import org.elasticsearch.core.IOUtils;
-import org.elasticsearch.search.vectors.IVFKnnSearchStrategy;
 
 import java.io.IOException;
 import java.util.function.IntPredicate;
@@ -244,11 +243,8 @@ public final void search(String field, float[] target, KnnCollector knnCollector
             rawVectorsReader.search(field, target, knnCollector, acceptDocs);
             return;
         }
-        if (fieldInfo.getVectorDimension() != target.length) {
-            throw new IllegalArgumentException(
-                "vector query dimension: " + target.length + " differs from field dimension: " + fieldInfo.getVectorDimension()
-            );
-        }
+        // TODO add new ivf search strategy
+        int nProbe = 10;
         float percentFiltered = 1f;
         if (acceptDocs instanceof BitSet bitSet) {
             percentFiltered = Math.max(0f, Math.min(1f, (float) bitSet.approximateCardinality() / bitSet.length()));
@@ -261,13 +257,6 @@ public final void search(String field, float[] target, KnnCollector knnCollector
             }
             return visitedDocs.getAndSet(docId) == false;
         };
-        final int nProbe;
-        if (knnCollector.getSearchStrategy() instanceof IVFKnnSearchStrategy ivfSearchStrategy) {
-            nProbe = ivfSearchStrategy.getNProbe();
-        } else {
-            // TODO calculate nProbe given the number of centroids vs. number of vectors for given `k`
-            nProbe = 10;
-        }
 
         FieldEntry entry = fields.get(fieldInfo.number);
         CentroidQueryScorer centroidQueryScorer = getCentroidScorer(