[Maintenance] Extract test setup/teardown helper for dom-using helpers

[NullVoxPopuli]

Original suggestion: #1113 (comment)

What to explore:

• if we can make all the dom-using tests use the same setup/teardown behaviors in a like setupDomTest(hooks) style helper.
  In particular, this code is repeated everywhere:

   if (element) {
     element.setAttribute('data-skip-steps', true);
     element.parentNode.removeChild(element);
     element = undefined;
   }