See Expedited delete

Given some PDHes of trashed collections...

For each PDH:

• Check for an un-trashed collection with this PDH. If one exists, show a warning: this means "expedited delete" for this collection is a no-op.
• Get the manifest text for this PDH from the trash.

Perform a keep-balance operation, but

• Don't compute changes for all blocks -- only the ones appearing in the manifests retrieved above.
• When checking trashed collections for recently referenced blocks (see #9363), skip collections with any of the supplied PDHes.
• When deciding whether to delete blocks, use the most recent timestamp of the collections being deleted rather than {now minus signatureTTL} as the race window threshold.
• Use the (new) "synchronous delete, ignoring timestamp" feature of keepstore instead of sending a trash list.
• Don't process any "pull" operations.
• If any blocks in the deleted collections are still referenced by other collections (either trashed or un-trashed), log the PDHes of the collections that prevent the data from being fully deleted.

This could be presented as a separate command ("keep-force-delete"?) if keep-balance is refactored into a module. Alternatively, it could be a runtime option for keep-balance. It will use the same configuration file as keep-balance (along with other options).