This moves the rollup cleanup code for http tests from the high level rest
client into the test framework and then entirely removes the rollup cleanup
code for http tests that lived in x-pack. This is nice because it
consolidates the cleanup into one spot, automatically invokes the cleanup
without the test having to know that it is "about rollup", and should allow
us to run the rollup docs tests.
Part of #34530
139bbc3f03