Upgrade Bazel to 2.2.0 in docker image

Change-Id: I34d3469650bbfa3d0147230bcf9cd1c14129be1e
diff --git a/jenkins-docker/slave-bazel-nocache/Makefile b/jenkins-docker/slave-bazel-nocache/Makefile
index f175d12..2bc47b3 100644
--- a/jenkins-docker/slave-bazel-nocache/Makefile
+++ b/jenkins-docker/slave-bazel-nocache/Makefile
@@ -1,6 +1,6 @@
 NO_CACHE=false
 IMAGE=gerritforge/gerrit-ci-slave-bazel:debian-stretch-nocache
-BAZEL_VER=2.1.0
+BAZEL_VER=2.2.0
 BUILDIFIER_VER=0.29.0
 BAZELISK_VER=1.1.0
 NODE_VER=10