backports: don't hardcode an old gpg key for Ubuntu

Same as #847 but for Ubuntu.

The gpg keys used to sign the Ubuntu repos, including backports, come
with standard Ubuntu installations, so this Puppet module doesn't need
to add any key.

Having this old key causes Puppet run failures for 20.04 and newer
machines without Internet access.

Author: kenyon

manifests/backports.pp

@@ -83,9 +83,6 @@
   unless $repos {
     $_repos = $apt::backports['repos']
   }
-  unless $key {
-    $_key =  $apt::backports['key']
-  }
 
   if $pin =~ Hash {
     $_pin = $pin

manifests/params.pp

@@ -88,7 +88,6 @@
     'Ubuntu': {
       $backports = {
         'location' => 'http://archive.ubuntu.com/ubuntu',
-        'key'      => '630239CC130E1A7FD81A27B140976EAF437D05B5',
         'repos'    => 'main universe multiverse restricted',
       }
       $ppa_options        = ['-y']

spec/classes/apt_backports_spec.rb

@@ -52,7 +52,6 @@
 
       it {
         expect(subject).to contain_apt__source('backports').with(location: 'http://archive.ubuntu.com/ubuntu',
-                                                                 key: '630239CC130E1A7FD81A27B140976EAF437D05B5',
                                                                  repos: 'main universe multiverse restricted',
                                                                  release: 'bionac-backports',
                                                                  pin: { 'priority' => 200, 'release' => 'bionac-backports' })