stack/lamp: Generate random password for mariadb

See merge request !1331
10 jobs for 1.0
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

passed SlapOS-Master.StandaloneDeploymentScriptTest-Debian.Buster

passed SlapOS.Eggs.UnitTest-Master.Python2

passed SlapOS.Eggs.UnitTest-Master.Python3

passed SlapOS.KVM.ResilienceTest-Master

failed SlapOS.SoftwareReleases.IntegrationTest-Master

passed SlapOS.Theia.ResilienceTest-Master

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster