Revert "Make qapt-deb-installer default app for all Debian packages."

This reverts commit 3917c6c927.

debian/changelog

@@ -1,9 +1,3 @@
-lubuntu-default-settings (21.04.1ubuntu1) hirsute; urgency=medium
-
-  * Make qapt-deb-installer default app for all Debian packages. 
-
- -- Walter Lapchynski <wxl@ubuntu.com>  Mon, 15 Feb 2021 13:25:16 -0800
-
 lubuntu-default-settings (21.04.1) hirsute; urgency=medium
 
   * Update XscreenSaver lock screen to 21.04.

src/etc/xdg/xdg-Lubuntu/mimeapps.list

@@ -8,7 +8,7 @@ application/pdf=qpdfview.desktop
 application/postscript=qpdfview.desktop
 application/rtf=libreoffice-writer.desktop
 application/tab-separated-values=libreoffice-calc.desktop
-application/vnd.debian.binary-package=qapt-deb-installer.desktop
+application/vnd.debian.binary-package=org.kde.discover.desktop
 application/vnd.flatpak=org.kde.discover.desktop
 application/vnd.flatpak.ref=org.kde.discover.desktop
 application/vnd.flatpak.repo=org.kde.discover.desktop