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

7 jobs for !2822 with fix/test-stokes-darcy-l2error in 7 minutes and 43 seconds (queued for 3 seconds)
Child pipeline (parent) latest detached
Status Name Job ID Coverage
  Configure
passed configure #36470

00:02:34

 
  Linting
passed black (python) #36474

00:01:04

passed pylint-flake8 (python) #36476

00:01:01

 
  Select
passed select tests #36479

00:03:02

 
  Build
passed compile cpp #36482

00:01:24

 
  Test
passed test cpp #36485

00:00:41

passed test python #36488

00:00:31