test: remove flaky status for cluster test
test: remove flaky status for cluster test

The test did not fail after 9999 runs in continuous integration.

Remove it's flaky status.

Fixes: https://github.com/nodejs/node/issues/2557
PR-URL: https://github.com/nodejs/node/pull/3975
Reviewed-By: Rod Vagg <f9f03903429036ef609ed7ca822fddfa76155c29@vagg.org>
Reviewed-By: Colin Ihrig <838f779c91673db29b8572ea3f54d191d3878ae2@gmail.com>
Reviewed-By: Ben Noordhuis <59bd0a3ff43b32849b319e645d4798d8a5d1e889@bnoordhuis.nl>
Reviewed-By: Roman Klauke <d817af1499bb518fdf015b00b45f20c6b53728ce@gmail.com>

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node