Backport fix for KDE bug 391706 into Frameworks 5.44

[Impact]

 * Kubuntu Bionic LTS released with KDE Frameworks 5.44, which included a bug in the Solid framework (https://bugs.kde.org/show_bug.cgi?id=391706) that breaks auto-mounting internal disks, among other things. The bug was fixed in KDE Frameworks 5.46 with https://cgit.kde.org/solid.git/commit/?id=122a6cd8989a4bd3096fddea908a1c2b223be62a. But Kubuntu did not get that fix because it was made after the Bionic release.

 * This causes user-facing bugs such as https://bugs.kde.org/show_bug.cgi?id=397911, where resources located on non-auto-mounted external disks are not available until the user manually mounts the disk.

[Test Case]

 * Have a second disk

 * Put an image file on the second disk

 * Use that image file as your Plasma wallpaper (Right-click on desktop > Configure Desktop > Set image as wallpaper)

 * Restart your computer. The image you set has been replaced with the default Plasma wallpaper because the disk it was located on was not available at the time when Plasma tried to find it because automounting is broken. This was reported by a user at https://bugs.kde.org/show_bug.cgi?id=397911 and verified by me.

[Regression Potential]

 * The fix was released to users 3 months ago, and since then KDE upstream has not had any reports of broken automount behavior, not any related regressions.