Bump buildifier version to 4.0.0

Change-Id: Icf5be2646e286c9a5b2218b2cad2d356cc1e517c
diff --git a/jenkins-docker/slave-bazel-nocache/Dockerfile b/jenkins-docker/slave-bazel-nocache/Dockerfile
index daab49b..2778f0a 100644
--- a/jenkins-docker/slave-bazel-nocache/Dockerfile
+++ b/jenkins-docker/slave-bazel-nocache/Dockerfile
@@ -17,7 +17,7 @@
     cd buildtools && \
     git checkout ${BUILDIFIER_VER} && \
     bazel build --config=release //buildifier && \
-    cp bazel-bin/buildifier/linux_amd64_stripped/buildifier /usr/bin && \
+    cp bazel-bin/buildifier/buildifier_/buildifier /usr/bin && \
     rm -rf /tmp/buildtools && \
     buildifier --version'
 
diff --git a/jenkins-docker/slave-bazel-nocache/Makefile b/jenkins-docker/slave-bazel-nocache/Makefile
index 8504915..92e24aa 100644
--- a/jenkins-docker/slave-bazel-nocache/Makefile
+++ b/jenkins-docker/slave-bazel-nocache/Makefile
@@ -3,7 +3,7 @@
 NO_CACHE=false
 IMAGE=gerritforge/gerrit-ci-slave-bazel:debian-buster-nocache
 BAZEL_VER=4.0.0
-BUILDIFIER_VER=3.5.0
+BUILDIFIER_VER=4.0.0
 BAZELISK_VER=1.7.4
 NODE_VER=10
 WCT_VER=6.8.0