test: move test-vm-function-redefinition to parallel

With the upstream fix in V8, function declarations now
work fine in the vm module and the test is no longer failing.

Refs: https://codereview.chromium.org/2334733002
Fixes: https://github.com/nodejs/node/issues/548
PR-URL: https://github.com/nodejs/node/pull/9618


Reviewed-By: Ali Ijaz Sheikh <ofrobots@google.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>