Identify post-apexd crashing processes

I7d47ea1223f7792a834981c729694242ab3f28c9 tried to identify processes that crash
after apexd is ready by introducing an 'updatable' class. However, after
I7ca67755dc0656c0f0c834ba94bf23ba9b1aca68 we now have a pre_apexd_ field we can
reuse instead of introducing a new class type.

Bug: 120598832
Test: Killing a !pre_apexd_ process 4 times in 4mins sets the
ro.init.updatable.crashing prop while killing a pre_apexd_ process reboots
into the bootloader

Change-Id: Icb9f405b9b54d11546bbf6d3bc28212936a78b0e