chore: add newlines to login banner message

[jackfrancis]

Reason for Change:

Add newlines to make things look nicer. From:

$ ssh -A -i _output/kubernetes-westus2-70830-ssh azureuser@kubernetes-westus2-70830.westus2.cloudapp.azure.com
Authorized uses only. All activity may be monitored and reported.Welcome to Ubuntu 16.04.6 LTS (GNU/Linux 4.15.0-1041-azure x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

0 packages can be updated.
0 updates are security updates.

New release '18.04.2 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

To:

$ ssh -A -i _output/kubernetes-westus2-17862-ssh azureuser@kubernetes-westus2-17862.westus2.cloudapp.azure.com

Authorized uses only. All activity may be monitored and reported.

Welcome to Ubuntu 16.04.6 LTS (GNU/Linux 4.15.0-1041-azure x86_64)

 * Documentation:  https://help.ubuntu.com
 * Management:     https://landscape.canonical.com
 * Support:        https://ubuntu.com/advantage

  Get cloud support with Ubuntu Advantage Cloud Guest:
    http://www.ubuntu.com/business/services/cloud

24 packages can be updated.
15 updates are security updates.

New release '18.04.2 LTS' available.
Run 'do-release-upgrade' to upgrade to it.

Issue Fixed:

Requirements:

• uses conventional commit messages
• includes documentation
• adds unit tests
• tested upgrade from previous version

Notes:

[codecov]

Codecov Report

Merging #1114 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1114   +/-   ##
=======================================
  Coverage   74.35%   74.35%           
=======================================
  Files         131      131           
  Lines       18274    18274           
=======================================
  Hits        13588    13588           
  Misses       3905     3905           
  Partials      781      781

[CecileRobertMichon]

/lgtm

[acs-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: CecileRobertMichon, jackfrancis

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