[MultiKueue] Support Long running services

[ravisantoshgudimetla]

What would you like to be added:
When a serving workload needs to move clusters (e.g., GPU type change), Multi-Kueue immediately deletes the old serving when quota moves, causing a service gap until the new serving is ready in the target cluster.
I know other long-running jobs like RayJobs might have similar concerns around service continuity.

Why is this needed:
For serving workloads, we'd ideally wait for the replacement to be "Ready" before cleaning up the old one to maintain service availability during cross-cluster transitions. There could be other replacements policies if needed

We can define a new interface:

type MultiKueueAdapterWithCleanupPolicy interface {
      MultiKueueAdapter
      CleanupPolicy() CleanupPolicy
  }

I am planning to use this interface(or a modification of that) and extending elasticJobs implementation to allow for what is a called a replacement workload slice.

Completion requirements:

This enhancement requires the following artifacts:

• Design doc
• API change
• Docs update

The artifacts should be linked in subsequent comments.

[mimowo]

cc @mwielgus @mwysokin

[olekzabl]

/area multikueue