[flatcar] add python dependency check for helm-apps (#10192)

* add pyyaml install via task instead of package

* Change condition for better consistency in the codebase

roles/kubernetes-apps/helm/tasks/main.yml

@@ -17,6 +17,11 @@
   package:
     name: "{{ pyyaml_package }}"
     state: present
+  when: pyyaml_package is defined
+
+- name: Helm | Install PyYaml [flatcar]
+  include_tasks: pyyaml-flatcar.yml
+  when: ansible_os_family in ["Flatcar", "Flatcar Container Linux by Kinvolk"]
 
 - name: Helm | Download helm
   include_tasks: "../../../download/tasks/download_file.yml"