Use new sandbox2::Comms ctor for default connection params
Use new sandbox2::Comms ctor for default connection params

This change allows Sandbox2 to change how the default FD for comms is chosen.

PiperOrigin-RevId: 479521810
Change-Id: Ia2ca1df95eb21783207ffb625c924790de20480d

google/sandboxed-api,google/sandboxed-api,google/sandboxed-api,google/sandboxed-api