wc-generator: update api js examples pattern to use event

[Izook]

General Support Request

For API demo examples that require JavaScript, we use the following snippet to determine if all content has been loaded onto the page:

function initSetUpExample() {
  try {
    setUpExample();
  } catch {
    if (initCount <= 20) {
      // setTimeout handles issue where content is sometimes loaded after the functions get called
      setTimeout(() => {
        initButtonApiExamples(initCount + 1);
      }, 100);
    }
  }
}

We should explore the possibility of waiting for an event (potentially onLoad) to load the content to improve the consistency of this snippet instead of trying repeatedly until the function succeeds.

Possible Solution

Await setting up demos until the onLoad event (or other more appropriate event) fires.

Additional context

https://github.com/AlaskaAirlines/auro-button/pull/214/files#r1223595594