When rapidly processing informer events it can happen that a pod gets scheduled
twice (seen only in the TestEviction/update unit test):
- Claim update observed, pod from informer cache with NodeName from update -> queue pod for eviction.
- Pod update observed, claim from informer cache -> queue pod again.
The effect is one additional Get call to the apiserver. We can avoid it by
maintaining an LRU cache with the UIDs of the pods which we have evicted and
thus don't need to do anything for.
