Remove the threshold barrier that prevented re-assignment to the same
promo group tier. Previously, _get_best_group_for_spending was called
with min_threshold_kopeks=previous_threshold, which meant once a user
was auto-assigned to a tier (e.g. 100 kopeks), the check 100 > 100
would fail and the function would skip cleanup of promocode groups.
Now the function always finds the best group for the user's spending
without threshold filtering. The threshold ratchet is preserved only
for the watermark update (auto_promo_group_threshold_kopeks only
increases, never decreases).
Also elevate promo group assignment failure logging from DEBUG to
WARNING across all 3 call sites in transaction.py.
Fringg
4a002b7db1