software/theia: Use slap-connection shared-parts

This will let a non-shared Theia (for example coming from shacache
binary) to be able to use the shared parts of a machine.

See merge request !1409
2 jobs for fix_tests
Status Job ID Name Coverage
  External
failed ERP5.StandaloneDeploymentScriptTest-Debian.Buster.Master

failed Wendelin.StandaloneDeploymentScriptTest-Debian.Buster.Master