DocumentPublisher doesn't handle PublishingAPI timeouts well

[fofr]

If Publishing API times out but still succeeds with publishing the document, when the document publisher retries the second call to publisher will error. The affect of this is that any of the subsequent code does not run - ie Rummager is not updated and no emails are sent.

specialist-publisher/app/services/document_publisher.rb

Lines 10 to 23 in d1d4649

	Services.publishing_api.publish(document.content_id)
	published_document = document.class.find(document.content_id)
	indexable_document = SearchPresenter.new(published_document)
	RummagerWorker.perform_async(
	document.search_document_type,
	document.base_path,
	indexable_document.to_json,
	)
	if document.send_email_on_publish?
	EmailAlertApiWorker.perform_async(EmailAlertPresenter.new(document).to_json)
	end

Found by @thomasleese when investigating:
https://govuk.zendesk.com/agent/tickets/2303234

[thomasleese]

Solved for Rummager #1063 but still a problem with emails.