COMPLIANCE-mode retention leaves objects that BypassGovernanceRetention cannot
clear, so the test's DeleteBucket keeps returning BucketNotEmpty and the
underlying SeaweedFS collection (with its 7 reserved volumes) leaks. After a
few leaks on the single-node `weed mini` server, the master logs "Not enough
data nodes found" and every subsequent PutObject 500s, timing the suite out.
Call the master's /col/delete admin endpoint from deleteBucket so the
collection's volumes are reclaimed even when S3-level cleanup is blocked.