Reverse logic of cookie removal (excl. Licensing)
Reverse logic of cookie removal (excl. Licensing)

Commit fa6a420 changed this condition from using `req.backend` to `req.url`.
In doing so I didn't read the comparison correctly and reversed the logic,
causing cookies to be removed from Licensing requests, the only application
which requires them, but not from everything else.

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