Re-enable chart testing

A previous change to move the linting job to helm3 removed the
chart testing role. This change adds it back.

Change-Id: Ifb8b1885b4dbe8d964f46347c8c510c743af91f4

playbooks/lint.yml

@@ -14,6 +14,14 @@
 # limitations under the License.
 
 - hosts: all
+  roles:
+    - ensure-chart-testing
+    - name: chart-testing
+      chart_testing_options: "--chart-dirs=. --validate-maintainers=false"
+      zuul_work_dir: "{{ work_dir }}"
+  vars:
+    work_dir: "{{ zuul.project.src_dir }}/{{ zuul_osh_infra_relative_path | default('') }}"
+
   tasks:
     - name: install helm3
       become_user: root