Fix the hour to for pagerduty_drill start.
Fix the hour to for pagerduty_drill start.

I changed the time that the drill stops in this PR:
https://github.gds/gds/puppet/pull/3166 but not
when the drill runs, meaning that it will run for
longer than intended. Fix this.

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