init: don't import rc files during mount_all after Q

Importing rc files during mount_all was at best a stop gap until
Treble's first stage mount and at worst a bad idea.  It doesn't have a
reason to exist now that first stage mount exists and is required, and
always had edge cases where init could not handle loading some aspects
of scripts after it had started processing actions.

This change removes this functionality for devices launching after Q.

Test: devices boot
Change-Id: I3181289572968637b884e150d36651f453d40362