HDDS-16213. Avoid the per-group list copy in KeyManagerImpl.getPendingDeletionKeys

[orca-07]

What changes were proposed in this pull request?

In KeyManagerImpl.getPendingDeletionKeys (the KeyDeletingService reclaimable-key scan), each key's DeletedBlock list is built via a flatten-copy that is immediately re-streamed and discarded, once per key in the scan:

List<DeletedBlock> deletedBlocks = info.getKeyLocationVersions().stream()
    .flatMap(versionLocations -> versionLocations.getLocationList().stream()
        .map(b -> new DeletedBlock(
            new BlockID(b.getContainerID(), b.getLocalID()),
            b.getLength(),
            QuotaUtil.getReplicatedSize(b.getLength(), info.getReplicationConfig()),
            QuotaUtil.getSizePerReplica(b.getLength(), info.getReplicationConfig())
        ))).collect(Collectors.toList());

Fix: use getLocationLists() (no copy): .flatMap(v -> v.getLocationLists().stream().flatMap(List::stream)). Behavior unchanged. Complementary to HDDS-16195, which reuses the computed replicated sizes on the same loop but leaves this copy in place.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-16213

How was this patch tested?

https://github.com/orca-07/ozone/actions/runs/32501303771

https://github.com/orca-07/ozone/actions/runs/32457228935

[chihsuan]

Thanks for the patch! @orca-07 +1 LGTM

[rich7420]

@orca-07 thanks for the patch! LGTM