This reverts commit bdac0595323a6417fb7365038c9777cde0060f58.

Many testers are seeing the

"I cannot read the partition table of device sda, it's too corrupted for me:("

message when the installer first examines the disks.
It's likely that when the installer examines the partition table on the
disk, that triggers the udev rule and causes the kernel to rescan the
partition table. Unfortunately this coincides with the installer reading
/proc/partitions to verify the kernel has the same view of the
partitions, which can catch /proc/partitions in a partially updated state.

After patching the ISO to remove the 60-block.rules file from stage 2,
no failures happen in the installer.