Remove platform tenancy from SXCHNGE customer BFF (#34)

backend/pkg/db/internal/mongo/transactionimp/transaction.go

@@ -12,6 +12,10 @@ type MongoTransaction struct {
 }
 
 func (mt *MongoTransaction) Execute(ctx context.Context, cb transaction.Callback) (any, error) {
+	// Reuse an outer customer workflow transaction when a token store joins it.
+	if transaction.ActiveMongoTransaction(ctx) {
+		return cb(ctx)
+	}
 	session, err := mt.client.StartSession()
 	if err != nil {
 		return nil, err