The bulk /sync/dell reuse check only matched an existing warranty when its
provider was exactly 'dell'. Warranties added by hand or via import default to
provider 'manual', so re-check-all did not recognize them and created a brand
new Dell warranty for every asset - duplicating the whole set.
Broaden the reuse match to treat a warranty as Dell by any signal (provider,
matching service tag, or a 'Dell' vendor), and canonicalize the reused row to
provider 'dell' so later re-checks match by provider and never duplicate.
19876a5640