api-limiter: Add stress test
api-limiter: Add stress test

Simulate stress by feeding many parallel requests through the API rate
limiter. The maximum wait duration will soon be hit for requests causing
them to fail.

Without the fix, this test would often fail. If it succeeded, the number
of retries is in the range of 60-80K. With the fix, the test succeeds
consistently and retries are in the range of 6-8K. That's a 10x
reduction of retries.

Signed-off-by: Thomas Graf <5f50a84c1fa3bcff146405017f36aec1a10a9e38@cilium.io>

cilium/cilium,tgraf/cilium,tgraf/cilium,michi-covalent/cilium,tgraf/cilium,cilium/cilium,michi-covalent/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,tklauser/cilium,cilium/cilium,michi-covalent/cilium,tgraf/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,michi-covalent/cilium,tklauser/cilium