Move xdg-autostart.target from Requires to Wants

This enables developers to force systemd boot even if there systemd
is too old.

startkde/systemd/plasma-workspace@.target

@@ -1,6 +1,6 @@
 [Unit]
 Description=KDE Plasma Workspace
-Requires=plasma-core.target xdg-desktop-autostart.target graphical-session.target
-Wants=plasma-kwin_%i.service plasma-restoresession.service plasma-xembedsniproxy.service plasma-gmenudbusmenuproxy.service plasma-powerdevil.service plasma-ksplash-ready.service plasma-polkit-agent.service kde-baloo.service plasma-foreground-booster.service plasma-kwallet-pam.service
+Requires=plasma-core.target graphical-session.target
+Wants=plasma-kwin_%i.service plasma-restoresession.service plasma-xembedsniproxy.service plasma-gmenudbusmenuproxy.service plasma-powerdevil.service plasma-ksplash-ready.service plasma-polkit-agent.service kde-baloo.service plasma-foreground-booster.service plasma-kwallet-pam.service xdg-desktop-autostart.target
 BindsTo=graphical-session.target
 Before=graphical-session.target xdg-desktop-autostart.target plasma-ksplash-ready.service plasma-restoresession.service