Remove libreoffice-kde5 because his file picker doesn't add file extension

Summary: Remove libreoffice-kde5, his filepicker doesn't add file extension as stated in bug 1812101

Test Plan: in live or installation try to save a file and look if file extension is added

Reviewers: wxl, tsimonq2

Reviewed By: wxl

Differential Revision: https://phab.lubuntu.me/D2

desktop

@@ -104,8 +104,7 @@ Task-Metapackage: lubuntu-desktop
  * (libreoffice-calc)
  * (libreoffice-impress)
  * (libreoffice-writer)
- * (libreoffice-kde5)
+ * (libreoffice-gtk3)               #lo-kde5 save dialog doesn't add extension, lo-qt isn't ready, see bug 1812101
- * (libreoffice-gtk3)
  * (libreoffice-style-breeze)
  * !libreoffice-gnome
  * (qpdfview)