PR-20822: [fix][broker] Avoid infinite bundle unloading

[streamnativebot]

url: apache#20822

Motivation

The bundle ownership assignment logic doesn't know the previous unloaded broker when unloading happens. It might assign the bundle to the same broker. In this case, it might cause an infinite bundle unloading loop.

To resolve this issue, we can check the destination broker when doing the doLoadShedding stage. When the destination broker is the same as the current owner broker, we can skip this unload, and if it is different, we set the new owner in this stage.

Modifications

• Transfer the bundle to the new owner when needed to unload.

Verifying this change

See the ModularLoadManagerImplTest#testLoadShedding unit test.

Documentation

• doc
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• doc-complete