Refactor Helm role test setup

Test setup variable inclusion reworked for better sanity.

General Molecule docker image is used instead of pre-built one.

Change-Id: I013b9d7b92ded86220e6f2092ce75ee47b094d89
Issue-ID: OOM-2665
Signed-off-by: Bartek Grzybowski <b.grzybowski@partner.samsung.com>
diff --git a/ansible/roles/helm/molecule/default/molecule.yml b/ansible/roles/helm/molecule/default/molecule.yml
index 0d46c2d..359d3ab 100644
--- a/ansible/roles/helm/molecule/default/molecule.yml
+++ b/ansible/roles/helm/molecule/default/molecule.yml
@@ -7,10 +7,7 @@
   name: yamllint
 platforms:
   - name: infrastructure-server
-    image: molecule-${PREBUILD_PLATFORM_DISTRO:-centos}:${PREBUILD_DISTRO_VERSION:-centos7.6}
-    pre_build_image: True
-    privileged: true
-    override_command: False
+    image: centos:7
     groups:
       - infrastructure
 provisioner:
@@ -25,7 +22,6 @@
       all:
         app_name: onap
         app_data_path: "/opt/{{ app_name }}"
-        helm_bin_dir: /usr/local/bin
 scenario:
   name: default
 verifier: