Remove the govuk_mysql::backup class
Remove the govuk_mysql::backup class

We stopped using this class in 19f06e64. Which was before the module was
renamed in e9bee2cf.

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