[Tests] Remove QueryStringQueryBuilderTests#toQuery class assertions (#32236)

Currently we check that the queries that QueryStringQueryBuilder#toQuery returns
is one out of a list of many Lucene query classes. This list has extended a lot over time,
since QueryStringQueryBuilder can build all sort of queries. This makes the test hard to 
maintain. The recent addition of alias fields which build a BlendedTermQuery show how
easy this test breaks. Also the current assertions doesn't add a lot in terms of catching
errors. This is why we decided to remove this check.

Closes #32234

Author: Christoph Büscher

server/src/test/java/org/elasticsearch/index/query/QueryStringQueryBuilderTests.java

@@ -42,7 +42,6 @@
 import org.apache.lucene.search.WildcardQuery;
 import org.apache.lucene.search.spans.SpanNearQuery;
 import org.apache.lucene.search.spans.SpanOrQuery;
-import org.apache.lucene.search.spans.SpanQuery;
 import org.apache.lucene.search.spans.SpanTermQuery;
 import org.apache.lucene.util.BytesRef;
 import org.apache.lucene.util.automaton.TooComplexToDeterminizeException;
@@ -51,7 +50,6 @@
 import org.elasticsearch.cluster.metadata.IndexMetaData;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.compress.CompressedXContent;
-import org.elasticsearch.common.lucene.search.MultiPhrasePrefixQuery;
 import org.elasticsearch.common.settings.Settings;
 import org.elasticsearch.common.unit.Fuzziness;
 import org.elasticsearch.common.xcontent.XContentBuilder;
@@ -74,7 +72,6 @@
 import static org.elasticsearch.index.query.QueryBuilders.queryStringQuery;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertBooleanSubQuery;
 import static org.elasticsearch.test.hamcrest.ElasticsearchAssertions.assertDisjunctionSubQuery;
-import static org.hamcrest.CoreMatchers.either;
 import static org.hamcrest.CoreMatchers.equalTo;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.instanceOf;
@@ -381,11 +378,7 @@ public QueryStringQueryBuilder mutateInstance(QueryStringQueryBuilder instance)
     @Override
     protected void doAssertLuceneQuery(QueryStringQueryBuilder queryBuilder,
                                        Query query, SearchContext context) throws IOException {
-        assertThat(query, either(instanceOf(TermQuery.class))
-            .or(instanceOf(BooleanQuery.class)).or(instanceOf(DisjunctionMaxQuery.class))
-            .or(instanceOf(PhraseQuery.class)).or(instanceOf(BoostQuery.class))
-            .or(instanceOf(MultiPhrasePrefixQuery.class)).or(instanceOf(PrefixQuery.class)).or(instanceOf(SpanQuery.class))
-            .or(instanceOf(MatchNoDocsQuery.class)));
+        // nothing yet, put additional assertions here.
     }
 
     // Tests fix for https://github.com/elastic/elasticsearch/issues/29403