//visibility:override is no longer needed for impl_library_visibility
to override visibility.
Removing this allows the defaults module to specify better defaults.
- Stub libraries are made publicly visible, via `visibility`
- Impl libraries are private by default, but visibility is extended
by the modules
Bug: 165017290
Test: m
Exempt-From-Owner-Approval: build refactor
Change-Id: Ibf35bfac5c99a21125f89ba10945f3364217b90f
46c47efca2