[BUG] Invalid HTTP response header sent with track event

Nobody has claimed this yet.

**Description/Screenshot**
The App Insights `track` call sometimes returns an invalid HTTP response header that triggers a message in dev tools. I suspect this has nothing to do with this repo, but I'm not sure where to report it.


`Invalid 'X-Frame-Options' header encountered when loading 'https://site.host.local/': 'allow' is not a recognized directive. The header will be ignored.`

**Steps to Reproduce**
Report an event which results in a call to the track endpoint (https://dc.services.visualstudio.com/v2/track)

- OS/Browser: Edge (Chromium)
- SDK Version [e.g. 22]:
- How you initialized the SDK:

**Expected behavior**
All HTTP response headers should be valid across browsers

`X-Frame-Options` only allows `DENY` or `SAMEORIGIN` (https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options)

**Additional context**
Seen in Edge (Chromium) only so far. The header is completely missing in Chrome and Firefox (all current versions)

**Firefox**

**Chrome**

The report points to the track endpoint, https://dc.services.visualstudio.com/v2/track, rather than a repository file or test. Start by verifying its response headers in Edge and comparing Chrome and Firefox; the issue is complete when ownership of the invalid header and a reproducible result are established.

Written by the indexing model from the issue text.