Remove missing and unnecessary proto build rules.
Remove missing and unnecessary proto build rules.

Reverts: e44ee82 https://github.com/tensorflow/adanet/commit/e44ee82fa2f7e2b56042040181a33ddcd5969543

Should fix: https://travis-ci.org/tensorflow/adanet/builds/517997613

PiperOrigin-RevId: 242746412

tensorflow/adanet,tensorflow/adanet