openharmony-linux-demo-dashboard.conf: Various configuration for the demo distro

* disable getty on tty1
* disable weston toolbar (as we are running only one app at boot)
* define the epiphany app to use (HomeAssistant)
* run the HomeAssistant epiphany app at boot

Signed-off-by: Andrei Gherzan <andrei.gherzan@huawei.com>