Global ratelimit test in the ratelimiter test-suite

[Bluenix2]

Summary

Recently in wumpy-rest a bug was found where the global ratelimit handling was incorrectly locking the ratelimiter after unlocking it. This was because the global ratelimiting is not tested in this test suite.

Global ratelimit tests were originally excluded because some ratelimiters may decide to not handle 429-responses but the global ratelimit is so important that it should be handled even in cases like these.