ag/16564596 will change default value to false.
Configure correct overlay configuration.
Bug: 212488775
Test: manual test & build
Change-Id: Iaf1a0a23dae69fde5995e591a757a8ef5374d5b5
Preinstalled overlays needn't be signed with the same cert
as the package it overlays, simply being preinstalled is
enough. Sign with the default cert instead for now, which
provides fewer special privileges.
Bug: 162195999
Test: verify values still overlaid correctly
Change-Id: I017491fd383551c5aadf8648edb900e0c12a27b8
