[Rollup] Replace RollupIT with a ESRestTestCase version

The old RollupIT was a node IT, an flaky for a number of reasons.
This new version is an ESRestTestCase and should be a little more robust.

This was added to the multi-node QA tests as that seemed like the most
appropriate location.  It didn't seem necessary to create a whole new
QA module.

Note: The only test that was ported was the "Big" test for validating
a larger dataset.  The rest of the tests are represented in existing
yaml tests.

Closes elastic#31258
Closes elastic#30232
Related to elastic#30290

Author: polyfractal