Coming from KubeVirt: https://github.com/kubevirt/community/pull/258

The descheduler eviction policy is built on top of the eviction API. The API currently does not support eviction requests that are not completed right away. Instead, any eviction needs to either succeed or be rejected in response. Nevertheless, there are cases where an eviction request is expected to only initiate eviction. While getting confirmation or rejection of the eviction initiation.

Upstream proposal: https://github.com/kubernetes-sigs/descheduler/pull/1354

*DoD*:

• [ ] the proposal is reviewed and approved by the project contributors and maintainers
• a new story for the implementation part is created and linked with the same epic as this story has

The current PoC implementation is located under https://github.com/ingvagabund/descheduler/tree/eviction-in-background-code.

*PoC TODO*:

• eviction in background based on annotation
• eviction in background cancellation and resuming
• internal cache of evictions in background in progress implemented
• limits per node and namespaces respected
• removal of pending evictions in progress
• e2e for the eviction in background (with kubevirt deployed to simulate various cases)
• integration with KubeVirt