[tests] Revert "[tests] Remove dbus-launc from script"

This reverts commit 9225ef88b6fb6a0690b842720efaf3c2cf458b63.

Instead of removing dependence to dbus-launch, a modified version of
dbus-launch without dependency to X11 will be provided later.
[tests] Add missing dependency to dbus-x11

dbus-x11 provides dbus-launch tool.