Enable binary XML by default.

This change enables the feature-flag which pivots most of the XML
data stored by the system_server to using a binary XML wire format.

Benchmarks have shown this binary format can be written over 4x
faster and parsed over 8x faster than human-readable XML while
seamlessly enabling client code to pivot between the two formats.

Bug: 171832118
Test: atest FrameworksServicesTests
Change-Id: Id43edc0627866aba55e580d17958c689a6cfcfad