test: move tick-processor tests to own directory

The tick-processor tests are inherently non-deterministic. They
therefore have false negatives from time to time. They also
sometimes leave extra processes running.

Move them to their own directory until these issues are sorted. Note
that this means that the tests will not be run in CI. Like the inspector
tests and other tests, they will have to be run manually when they are
wanted.

PR-URL: https://github.com/nodejs/node/pull/9506


Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Matthew Loring <mattloring@google.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>