Remove vendor_init from coredomain

vendor_init exists on the system partition, but it is meant to be an
extention of init that runs with vendor permissions for executing
vendor scripts, therefore it is not meant to be in coredomain.

Bug: 62875318
Test: boot walleye
Change-Id: I01af5c9f8b198674b15b90620d02725a6e7c1da6