Fix typo in path to check_reboot_required Nagios plugin script
Fix typo in path to check_reboot_required Nagios plugin script

- Follow-up to d45682a because of
https://sentry.io/organizations/govuk/issues/1512657681/?environment=default&project=125252&query=is%3Aunresolved.

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