[Datasource Editor] A few small UI changes in modal to prevent accidental edits (#8471)

superset/assets/spec/javascripts/datasource/DatasourceEditor_spec.jsx

@@ -91,6 +91,7 @@ describe('DatasourceEditor', () => {
   });
 
   it('renders isSqla fields', () => {
+    wrapper.setState({ activeTabKey: 4 });
     expect(wrapper.state('isSqla')).toBe(true);
     expect(wrapper.find(Field).find({ fieldKey: 'fetch_values_predicate' }).exists()).toBe(true);
   });