Resolve "Dynamic Element Validation Iteration: Improve waiting"

What does this MR do?

Changes our Element Validation to use our built-in waiter.

Previously if a page had required: true, it would simply wait 60 seconds for that element to appear.

Now we will wait a total of 60 seconds for that element to appear, with 15 second intervals.

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content

Availability and Testing

This change, while helping the tests be less flaky, will also increase test run-time. The payoff is of course worth it, but it's good to be aware.

Closes #29033 (closed)