CORS violation when not using proxy

[kmcginnes]

Some public endpoints can not be queried due to CORS issues.

For example:

https://id.nlm.nih.gov/mesh

Problem

We add the queryId to requests in the header so that the proxy server can cancel the request if needed. But some public endpoints don't recognize that custom header and will reject the request.

We only need the queryId when using the proxy server.