[#60945276] Blacklist MySQL for unattended upgrade
[#60945276] Blacklist MySQL for unattended upgrade

Blacklists MySQL from being upgraded automatically. Upgrading MySQL
requires the service to be restarted, which could be a single point of
failure.

alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet,alphagov/govuk-puppet