Add tests for whether mixin output is checked-in

With the proposed workflow mixin output is generated offline and
checked into version control for direct usage.
A test is added to check whether the generated rules and dashboards
match the checked-in version.
Additionally checks for the shellscript generating the mixins and for
the mixin test playbook from above are added.

Signed-off-by: Jan Horstmann <horstmann@osism.tech>

.src/playbooks/mixin-ouput-ensure-git-checkin.yml

@@ -0,0 +1,38 @@
+---
+- name: Run check-shell-syntax
+  connection: local
+  hosts: localhost
+  #hosts: all
+  vars:
+    zuul:
+      project:
+        src_dir: ../..
+  tasks:
+    - name: Build monitoring-mixin container
+      containers.podman.podman_image:
+        name: mixin-builder
+        path: "./{{ zuul.project.src_dir }}/.src"
+        build:
+          file: "./{{ zuul.project.src_dir }}/.src/Containerfile"
+    - name: Install monitoring-mixin dependencies
+      containers.podman.podman_container:
+        command: jb install
+        <<: &mixin_container_options
+          name: mixin-builder
+          image: localhost/mixin-builder
+          detach: false
+          volume:
+            - "./{{ zuul.project.src_dir }}:/srv"
+          rm: true
+    - name: Render monitoring-mixin rules / dashboards
+      containers.podman.podman_container:
+        <<: *mixin_container_options
+    - name: Check difference between git and generated rules / dashboards
+      ansible.builtin.command:
+        argv:
+          - /usr/bin/git
+          - diff
+          - --exit-code
+      register: git_diff
+      changed_when: false
+      failed_when: git_diff.rc != 0

.zuul.yaml

@@ -5,9 +5,4 @@
     check:
       jobs:
         - yamllint
-    gate:
-      jobs:
-        - yamllint
-    periodic-daily:
-      jobs:
-        - yamllint
+        - name: ansible-lint