test: remove obsolete domain test

test-microtask-queue-run-immediate-domain.js tests that the behavior of
another test, test-microtask-queue-run-immediate.js, is still
consistent when the core domain module is loaded.

This was needed because before the changes in
nodejs/node#1622 were merged, the core domain
module would replace the function that would call nextTick callbacks
with a different implementation.

This is no longer the case, and as such that test is no longer needed.

Refs: nodejs/node#16222