message: remove unused preconditioner in LowerTrs
diff: @@ -108,12 +108,6 @@ public:
  GKO_CREATE_FACTORY_PARAMETERS(parameters, Factory)
  {
  - /**
  - * Preconditioner factory.
  - */
  - std::shared_ptr<const LinOpFactory> GKO_FACTORY_PARAMETER(
  - preconditioner, nullptr);
  -
  /**
  * Number of right hand sides.
  *
  