If `uris` is not in VCAP_SERVICES check `uri`
If `uris` is not in VCAP_SERVICES check `uri`

This commit fixes a bug found during the procees of migrating PREVIEW to 
elasticsearch from Aiven (see https://trello.com/c/k6OgT7v4/)

alphagov/digitalmarketplace-search-api,alphagov/digitalmarketplace-search-api