mariadb: build without tests to save space

This saves 380MB, by removing:
- bin/mysql_client_test (and the bin/mariadb-client-test symlink)
- mysql-test/
22 jobs for master in 0 seconds
Status Job ID Name Coverage
  External
passed Cloudooo.UnitTest-Master

00:18:00

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

01:18:08

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

06:57:27

passed SlapOS.Eggs.UnitTest-Master.Python2

00:27:55

passed SlapOS.Eggs.UnitTest-Master.Python3

00:21:05

passed SlapOS.Eggs.UnitTest-Master.Python3Next

00:33:25

failed SlapOS.SoftwareReleases.IntegrationTest-Master

05:32:05

passed SlapOS.Theia.ResilienceTest-Master-ERP5

06:23:44

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:31:48

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

07:43:46

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

01:43:48

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

01:27:26

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

01:24:09

passed ERP5.StandaloneDeploymentScriptTest-Debian.Buster

01:24:36

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:32:19

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:40:48

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:31:34

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster

00:32:32

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

06:52:13

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

06:42:11

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

06:42:11

passed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master

07:13:33