Move deprecated-ota code into a separate soong namespace

This offers better isolation, and allows two targets with the same name
to coexist(in different namespaces). During migration there will
be a short period of time where we have two copies of non-AB code.

Test: th
Bug: 324360816
Change-Id: I7b997f3d75a23ab8a750787d28d391c1bcfbab32