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Upgrade RabbitMQ module to latest version

Which is 4.0.0. There's no need to pin the version in `Puppetfile` as
the version is already pinned by the `Puppetfile.lock`.

Changes made by running:
```bash
librarian-puppet update puppetlabs/rabbitmq
```
RabbitMQ is not installed from our PPA

We are installing RabbitMQ from Ubuntu's archive:

```bash
ci-slave-2:~$ apt-cache policy rabbitmq-server
rabbitmq-server:
  Installed: 2.7.1-0ubuntu4
  Candidate: 2.7.1-0ubuntu4
  Version table:
 *** 2.7.1-0ubuntu4 0
        500 http://archive.ubuntu.com/ubuntu/ precise/main amd64 Packages
        100 /var/lib/dpkg/status
```
Use Aptly repo for RabbitMQ

Use the GOV.UK Aptly repository for RabbitMQ packages so that we can use
version 3.x. Pin the version to 3.3.4-1 to keep CI builds as consistent
as possible.

Note that `include_src` is set to false because we don't supply source
packages in our Aptly repo.

For more details please see:
https://github.gds/pages/gds/opsmanual/infrastructure/debian-packaging.html

Based on:
https://github.gds/gds/puppet/commit/bece0d52e59b4a1dbe5f587d857e00b3bb4ede5f
Merge pull request #177 from alphagov/70510370-rabbitmq

[#70510370] Use Aptly repo for RabbitMQ