the extractPotentialBuckets TODO asked to handle non-adjacent label
combos and strip the tld. strip the trailing tld label so we stop
guessing it ("com", "com-s3", "example-com"), and pair every label
with every other rather than only adjacent ones, so a deep host like
shop.cdn.example yields shop-example too.
this widens the candidate set (and the s3 probes) per host. multi-part
suffixes like .co.uk still leave a junk label; publicsuffix would
refine that as a follow-up.