CORD-1864: Corebuilder installing xproto parser in Dockerfile

Change-Id: Ib894470a69ade12c1eae19f469844212f902a12d
(cherry picked from commit 6746d62b650f43eedb83d5ed3946b09ed255ab3f)
diff --git a/containers/xos/Dockerfile.corebuilder b/containers/xos/Dockerfile.corebuilder
index 7cf3a34..0e1d0fc 100644
--- a/containers/xos/Dockerfile.corebuilder
+++ b/containers/xos/Dockerfile.corebuilder
@@ -34,9 +34,6 @@
       org.label-schema.build-date=$org_label_schema_build_date \
       org.opencord.vcs-commit-date=$org_opencord_vcs_commit_date
 
-# Temporary fix. This should go away when we update xos-core to a more recent image.
-RUN pip install git+https://github.com/sb98052/plyprotobuf
-
 ENV HOME /root
 WORKDIR /opt/xos/tools/corebuilder