Revert "Mark objects/stables with index in deserialize."

This reverts commit 478542413715c5e5fae2bd0c172371e343a536cb. This is
the commit to blame for the Panda build breakage. Reverting it loses
us a bit of the CORE.setting build time win, but we get to keep most
of it. Can re-instate this later; need to better understand why it
breaks the Panda build.