Port plasma-workspace to autoconfig.kde.org

As per Ben's request in https://mail.kde.org/pipermail/kde-frameworks-devel/2020-January/102543.html

Differential Revision: https://phabricator.kde.org/D27021

components/shellprivate/widgetexplorer/plasmoids.knsrc

@@ -39,7 +39,7 @@ Name[x-test]=xxPlasma Widgetsxx
 Name[zh_CN]=Plasma 部件
 Name[zh_TW]=Plasma 元件
 
-ProvidersUrl=https://download.kde.org/ocs/providers.xml
+ProvidersUrl=https://autoconfig.kde.org/ocs/providers.xml
 Categories=Plasma 5 Plasmoid
 StandardResource=tmp
 InstallationCommand=kpackagetool5 --install %f --type Plasma/Applet

wallpapers/image/wallpaper.knsrc

@@ -38,7 +38,7 @@ Name[x-test]=xxWallpapersxx
 Name[zh_CN]=壁纸
 Name[zh_TW]=桌布
 
-ProvidersUrl=https://download.kde.org/ocs/providers.xml
+ProvidersUrl=https://autoconfig.kde.org/ocs/providers.xml
 Categories=KDE Wallpaper 800x600,KDE Wallpaper 1024x768,KDE Wallpaper 1280x1024,KDE Wallpaper 1440x900,KDE Wallpaper 1600x1200,KDE Wallpaper (other)
 StandardResource=wallpaper
 Uncompress=archive