[publishing-api] Enable new-style logging
[publishing-api] Enable new-style logging

This updates the log collection to collect the application logs from
stdout and stderr instead of reading from logfiles that the app creates
itself.

This includes a cleanup of the removal of an earlier STDOUT logstream
from when this was a Go application.

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