Switch the default from non-driver to driver in several tests

pkg/analysis_server/test/services/index/index_unit_test.dart

Index: pkg/analysis_server/test/services/index/index_unit_test.dart
diff --git a/pkg/analysis_server/test/services/index/index_unit_test.dart b/pkg/analysis_server/test/services/index/index_unit_test.dart
index c2254116f67f07a5522bffb9b6afbfdff157af0f..57f0525e2a43d60e412b99398755ff91b5974493 100644
--- a/pkg/analysis_server/test/services/index/index_unit_test.dart
+++ b/pkg/analysis_server/test/services/index/index_unit_test.dart
@@ -42,6 +42,9 @@ class PackageIndexAssemblerTest extends AbstractSingleUnitTest {
   PackageIndex packageIndex;
   UnitIndex unitIndex;
 
+  @override
+  bool get enableNewAnalysisDriver => false;
+
   _ElementIndexAssert assertThat(Element element) {
     List<_Relation> relations = _getElementRelations(element);
     return new _ElementIndexAssert(this, element, relations);