Merge changes from topic "rhel79-upgrade"

* changes:
  [DOC] Update Rhel/Centos version in docs to 7.9
  [ANSIBLE] Disable DNS management in Network Manager only if it's installed
  [CICDANSIBLE] Update heat template "image_name" parameter description
  [MOLECULE] Upgrade roles tests image to Centos7.9
  [MOLECULE] Upgrade playbook tests image to Centos7.9
  [BUILD] Run Centos7.9 docker image for rpm download

diff --combined tools/cicdansible/heat/installer.yaml
index 04f0deb,b0e5d26..101c526
--- 1/tools/cicdansible/heat/installer.yaml
--- 2/tools/cicdansible/heat/installer.yaml
+++ b/tools/cicdansible/heat/installer.yaml
@@@ -29,7 -29,7 +29,7 @@@ parameters
          description: "need to specify a valid flavor"
    image_name:
      label: "image name"
-     description: "name of the image from which to create all instances, should be rhel 7.6 or centos image"
+     description: "name of the image from which to create all instances, should be rhel/centos 7.9 image"
      type: string
      constraints:
        - custom_constraint: glance.image
@@@ -103,10 -103,6 +103,10 @@@
      type: string
      description: "specifies id of network used for demo usecases"
      default: ""
 +  docker_storage_size:
 +    label: "nodes' docker storage size"
 +    type: number
 +    description: "Size of the volume for the docker storage on nodes"
  conditions:
    #Condition for nfs volume usage.
    use_volume_for_nfs: { get_param: use_volume_for_nfs }
@@@ -216,7 -212,6 +216,7 @@@ resources
            notify_command: { get_attr: ["instance_wait_handle", "curl_cli"] }
            security_group: { get_resource: secgroup }
            demo_network: { get_param: demo_network }
 +          docker_storage_size: { get_param: docker_storage_size }
            scheduler_hints:
              group: { get_resource: anti_affinity_group }
      depends_on: [routercon, instance_wait_handle]