fix: plasmoid/kded wrong TRANSLATION_DOMAIN name

- kdisplay TRANSLATION_DOMAIN is no longer needed.
- i18nd is not needed because daemon and plasmoid share the same
TRANSLATION_DOMAIN.
- rename kdisplay-plasma-integration to plasma_applet_org.kwinft.kdisplay
- rename kdisplay-plasma.po(t) to plasma_applet_org.kwinft.kdisplay.po(t)