Don't re-show the bootloader for < 5 minute sessions

This isn't necessarily evidence of instability.

Related to #471

mkosi.extra/usr/lib/auto-hide-bootloader

@@ -14,11 +14,6 @@ case "${1:-}" in
             echo "Multiple operating systems detected, not hiding bootloader."
             exit 0
         fi
-        UPTIME_SECONDS="$(cut -d. -f1 /proc/uptime)"
-        if [ "$UPTIME_SECONDS" -lt 300 ]; then
-            echo "System uptime was less than 5 minutes, not hiding bootloader."
-            exit 0
-        fi
         if [ "$(systemctl show -p Result --value kde-linux-bless-boot.service 2>/dev/null || echo "failed")" = "success" ]; then
             /usr/bin/bootctl set-timeout 0
         fi

mkosi.extra/usr/lib/systemd/system/kde-linux-bless-boot.service

@@ -11,7 +11,7 @@ Before=shutdown.target
 Type=oneshot
 RemainAfterExit=yes
 ExecStart=/usr/lib/systemd/systemd-bless-boot good
-# If the boot was blessed, the user shuts the system down normally, and the uptime
-# is greater than 5 minutes, the bootloader is hidden, because the current image should work.
+# If the boot was blessed and the user shuts the system down normally,
+# the bootloader is hidden, because the current image should work.
 # This is idempotent if more than one operating system is installed.
 ExecStopPost=/usr/lib/auto-hide-bootloader hide