[test][md] Use new error helper in convergence test

5 jobs for !2822 with fix/test-stokes-darcy-l2error
latest detached
Status Name Job ID Coverage
  Trigger
passed full-dune-2.7-clang

passed full-dune-2.7-gcc

passed full-dune-master-gcc

passed minimal-dune-2.7-gcc

 
  Downstream Modules
passed trigger lecture