multi: move failed attempt cfg option to the router subsytem

Previously we had db and application logic mixed on the db level.
We now move the config option KeepFailedPaymentAttempts to the
ChannelRouter level and move it out of the db level.

payments/db/sql_store.go

@@ -99,10 +99,6 @@ type BatchedSQLQueries interface {
 type SQLStore struct {
 	cfg *SQLStoreConfig
 	db  BatchedSQLQueries
-
-	// keepFailedPaymentAttempts is a flag that indicates whether we should
-	// keep failed payment attempts in the database.
-	keepFailedPaymentAttempts bool
 }
 
 // A compile-time constraint to ensure SQLStore implements DB.
@@ -130,9 +126,8 @@ func NewSQLStore(cfg *SQLStoreConfig, db BatchedSQLQueries,
 	}
 
 	return &SQLStore{
-		cfg:                       cfg,
-		db:                        db,
-		keepFailedPaymentAttempts: opts.KeepFailedPaymentAttempts,
+		cfg: cfg,
+		db:  db,
 	}, nil
 }
 
@@ -1094,10 +1089,6 @@ func (s *SQLStore) FetchInFlightPayments(ctx context.Context) ([]*MPPayment,
 //   - StatusSucceeded: Can delete failed attempts (payment completed)
 //   - StatusFailed: Can delete failed attempts (payment permanently failed)
 //
-// If the keepFailedPaymentAttempts configuration flag is enabled, this method
-// returns immediately without deleting anything, allowing failed attempts to
-// be retained for debugging or auditing purposes.
-//
 // This method is idempotent - calling it multiple times on the same payment
 // has no adverse effects.
 //
@@ -1109,15 +1100,6 @@ func (s *SQLStore) FetchInFlightPayments(ctx context.Context) ([]*MPPayment,
 func (s *SQLStore) DeleteFailedAttempts(ctx context.Context,
 	paymentHash lntypes.Hash) error {
 
-	// In case we are configured to keep failed payment attempts, we exit
-	// early.
-	//
-	// TODO(ziggie): Refactor to not mix application logic with database
-	// logic. This decision should be made in the application layer.
-	if s.keepFailedPaymentAttempts {
-		return nil
-	}
-
 	err := s.db.ExecTx(ctx, sqldb.WriteTxOpt(), func(db SQLQueries) error {
 		dbPayment, err := fetchPaymentByHash(ctx, db, paymentHash)
 		if err != nil {