Reduce framework-connectivity footprint

Cleanup framework-connectivity to reduce its memory and storage usage:
 - Build libframework-connectivity-jni using standard C and removing
   dependencies on libc++. This saves about 100kB of storage (40+60kB
   on the 32+64 bit variants).
 - Remove dependency on protobuffer libraries, as their usage has been
   removed. This saves about 15kB of storage.

From local measurements, the reduced code size also improves memory
usage.

This also removes a jarjar workaround for net-utils-device-common, as
the library is no longer used either.

Bug: 184111895
Test: device boots, connectivity working
Change-Id: Ibfbd0fe1098293812ae24812621752a7a44f9130