[yaml-tests] Fix yaml test runtime cluster cleanup

[swallez]

Fixes several aspects of yaml-tests cluster cleanup:

• add addtional steps to clean up data streams
• reorganize steps (e.g. remove templates after deleting indices)
• always check response status codes, which uncovered a number of failing clean-ups that have been fixed.

Also adds minor fixes to the yaml-test runner engine.

This allowed to reduce the number of skipped tests.