Stick to Bazel/Debian nodes for code style check

The VM with Bazel/Debian is the main slave image that gets
updated and contains the latest GJF version installed.

Change-Id: I79db1b510ce3a1192e3b86a93377bc23e081e260
diff --git a/jenkins/gerrit-verifier.yaml b/jenkins/gerrit-verifier.yaml
index 2d63401..9fe0395 100644
--- a/jenkins/gerrit-verifier.yaml
+++ b/jenkins/gerrit-verifier.yaml
@@ -153,6 +153,7 @@
     name: Gerrit-codestyle
     description: "Gerrit code-style checker for an open change\n"
     defaults: verifier-defaults
+    node: bazel-debian
 
     builders:
       - merge-target-branch