mariadb: update MDEV-20693 mixin for versions 10.3 & 10.4

It was broken since commit 92779bf4.
4 jobs for master
Status Job ID Name Coverage
  External
running SlapOS.Eggs.UnitTest-Master.Python2

31312:56:43

passed SlapOS.Eggs.UnitTest-Master.Python3

00:10:22

running SlapOS.SlapRunner.ResilienceTest-Master

31312:56:09

running SlapOS.SlapRunner.ResilienceTest-Master.ERP5

31312:56:01