KMountPoint: revert to parsing /dev/disk/by-{uuid,label}/ manually
Apparently libblkid is causing some performance issues when resolving UUID/LABEL tags from fstab when the device that has that UUID/LABEL isn't present.
Parsing /dev/disk/by-* is more basic, since it's a simple check resolving some symlinks.
Thanks to the users in the bug report for the investigative work, because personally I couldn't reproduce the problem on my machine no matter what I tried.
BUG: 442106 FIXED-IN: 5.88