Fix NormalizerAgg test searcher wrapping (#57171)

The searcher was randomly wrapping its reader as slow, parallel, or filtered.
This was causing casting issues in the normalizer tests. By removing the
wrapping, the problem goes away.

Closes #57164

x-pack/plugin/analytics/src/test/java/org/elasticsearch/xpack/analytics/normalize/NormalizeAggregatorTests.java

@@ -160,7 +160,7 @@ private void testCase(ValuesSourceAggregationBuilder<?> aggBuilder, Consumer<Int
             termFieldType.setHasDocValues(true);
 
             try (IndexReader indexReader = DirectoryReader.open(directory)) {
-                IndexSearcher indexSearcher = newSearcher(indexReader, true, true);
+                IndexSearcher indexSearcher = newIndexSearcher(indexReader);
                 InternalAggregation internalAggregation = searchAndReduce(indexSearcher, query, aggBuilder, dateFieldType,
                     valueFieldType, termFieldType);
                 aggAssertion.accept(internalAggregation);