Remove sync-asset-manager-from-master cron job from asset slave
Remove sync-asset-manager-from-master cron job from asset slave

This cron job was marked as 'absent' in this PR [1] which has been
applied in all environments and so it's now safe to remove the
definition.

[1]: https://github.com/alphagov/govuk-puppet/pull/7016

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