Remove apt pinning task for debian buster

Buster is no longer supported on recent OSA releases so this task
is not required.

Change-Id: I96332980798cb56f725b8bdc9a0514ab40c1a0f9

meta/main.yml

@@ -36,5 +36,3 @@ galaxy_info:
     - nova
     - development
     - openstack
-dependencies:
-  - apt_package_pinning

tasks/nova_install.yml

@@ -25,23 +25,6 @@
     filter: ansible_local
     gather_subset: "!all"
 
-- name: Set apt package pins
-  include_role:
-    name: apt_package_pinning
-  vars:
-    apt_package_pinning_file_name: "qemu_backports.pref"
-    apt_package_pinning_priority: "1000"
-    apt_pinned_packages: [{ package: "{{ nova_backports_packages | join(' ') }}", release: 'Debian Backports' }]
-  when:
-    - ansible_facts['distribution'] | lower == 'debian'
-    - ansible_facts['distribution_version'] == '10'
-  args:
-    apply:
-      tags:
-        - nova-install
-  tags:
-    - always
-
 - name: Install distro packages
   package:
     name: "{{ nova_package_list }}"