CI: Add chart build job for latest Helm toolkit

This commit introduces a non-voting job to lint Helm charts against the
latest version of Helm toolkit from OpenStack-Helm Infra. This job
should serve as an indicator of when it's safe to advance the version of
Helm toolkit used by Airship.

Additionally, this commit modifies all Helm chart lint jobs to run on
each commit, regardless of the files modified by a change. This should
not introduce a noticeable difference in CI runtime, as these jobs
execute quicker than the tox jobs.

Change-Id: I0b38ef3388629b88ea6d6f88eabdc2d7f5f69a3b

.zuul.yaml

@@ -17,7 +17,8 @@
         - airship-promenade-lint-ws
         - airship-promenade-docker-build-gate
         - airship-promenade-doc-build
-        - airship-promenade-lint-chart
+        - airship-promenade-chart-build-gate
+        - airship-promenade-chart-build-latest-htk
         - airship-promenade-unit-py35
 
     gate:
@@ -26,7 +27,7 @@
         - airship-promenade-lint-ws
         - airship-promenade-docker-build-gate
         - airship-promenade-doc-build
-        - airship-promenade-lint-chart
+        - airship-promenade-chart-build-gate
         - airship-promenade-unit-py35
 
     post:
@@ -48,14 +49,23 @@
     nodeset: airship-promenade-single-node
 
 - job:
-    name: airship-promenade-lint-chart
+    name: airship-promenade-chart-build-gate
     description: |
-      Lints Helm charts for validity
+      Lints charts using pinned HTK
     run: tools/zuul/playbooks/helm-linter.yaml
     timeout: 300
     nodeset: airship-promenade-single-node
-    files:
+
-      - ^charts/.*$
+- job:
+    name: airship-promenade-chart-build-latest-htk
+    description: |
+      Lints charts using latest HTK
+    voting: false
+    run: tools/zuul/playbooks/helm-linter.yaml
+    timeout: 300
+    nodeset: airship-promenade-single-node
+    vars:
+      HTK_COMMIT: master
 
 - job:
     name: airship-promenade-unit-py35

tools/zuul/playbooks/helm-linter.yaml

@@ -13,9 +13,11 @@
 
 - hosts: primary
   tasks:
-    - name: Execute the make target for Helm chart linting
+    - name: Execute the make target to package Helm charts.
       make:
         chdir: "{{ zuul.project.src_dir }}"
-        target: helm-lint
+        target: charts
+        params:
+          HTK_COMMIT: "{{ HTK_COMMIT | default('') }}"
       register: result
       failed_when: result.failed