[ussuri-only] Add ensure-rust to grenade jobs

Grenade jobs started to fail on older branches (ussuri and train) as
pypi cannot fetch pre-built wheel for cryptography anymore and while
building it during the test job run it lacks rust compiler.

This patch adds ensure-rust as a workaround to be able to build the
wheels and make the grenade job functional again.

Change-Id: I43f6cf95da6b22ee3fb460929685e76d162329c6

.zuul.yaml

@@ -147,6 +147,7 @@
 - job:
     name: grenade
     parent: grenade-base
+    pre-run: playbooks/multinode-pre.yaml
     description: |
       Default grenade job
 

playbooks/multinode-pre.yaml

@@ -0,0 +1,3 @@
+- hosts: controller
+  roles:
+    - ensure-rust