[Feature]: Support KV offloading + PCP/DCP

[orozery]

🚀 The feature, motivation and pitch

Currently, PCP/DCP does not work with --kv-offloading-size (using the offloading connector).
See #40259 (comment) for example.

Investigate whether we can extend support for that.

Alternatives

No response

Additional context

No response

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[orozery]

cc @Etelis

[Etelis]

I'll focus on this next.
Thanks!