reporting: Unbound DNS database backup can take up a lot of storage space -- delete after restore?

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Describe the bug

https://forum.opnsense.org/index.php?topic=40621.0

The database export can leave excessively large files on the disk and it is not removed after a (successful) restore operation.

To Reproduce

Record a lot of queries... but in general any major upgrade will leave the full backup under /var/cache/unbound.duckdb regardless of its size.

Expected behavior

Clear the backup in the good recovery case perhaps. Maybe also drop the backup location when resetting the database from the GUI action.

Describe alternatives you considered

N/A

Screenshots

N/A

Relevant log files

N/A

Additional context

N/A

Environment

Any recent version with a major upgrade done and the database active.

opnsense / core