Simplify our export/delete clicks in jest tests

The less we assume about the UI, the more robust these'll be.

Author: rylnd

x-pack/plugins/security_solution/public/detections/components/value_lists_management_modal/modal.test.tsx

@@ -96,9 +96,8 @@ describe('ValueListsModal', () => {
 
       act(() => {
         container
-          .find('tbody tr')
-          .first()
           .find('button[data-test-subj="action-export-value-list"]')
+          .first()
           .simulate('click');
         container.unmount();
       });
@@ -120,9 +119,8 @@ describe('ValueListsModal', () => {
 
       act(() => {
         container
-          .find('tbody tr')
-          .first()
           .find('button[data-test-subj="action-delete-value-list"]')
+          .first()
           .simulate('click');
         container.unmount();
       });