Change EngineTestCase to not wrap the reader. (elastic#98732)

As part elastic#98110, EngineTestCase now uses newSearcher() to create a new
index searcher (instead of just creating a new index searcher). This is
for increasing test coverage. However, this test can't deal with
wrapping the index reader as it leads to assertion errors. So instead
use `newSearcher(leaf, false)` to still keep to test benefits of
wrapping the index searcher.

Closes elastic#98716

test/framework/src/main/java/org/elasticsearch/index/engine/EngineTestCase.java

@@ -1513,7 +1513,7 @@ public MatchingDirectoryReader(DirectoryReader in, Query query) throws IOExcepti
                 @Override
                 public LeafReader wrap(LeafReader leaf) {
                     try {
-                        final IndexSearcher searcher = newSearcher(leaf);
+                        final IndexSearcher searcher = newSearcher(leaf, false);
                         searcher.setQueryCache(null);
                         final Weight weight = searcher.createWeight(query, ScoreMode.COMPLETE_NO_SCORES, 1.0f);
                         final Scorer scorer = weight.scorer(leaf.getContext());