Reports fail when PDF generation request includes `Transfer-Encoding` HTTP header

[stacey-gammon]

On master, it seems I can no longer generate reports. Looking at #10353 it seems it may be an http/https issue. I am running es via yarn es snapshot --license trial and kibana with yarn start.

Trying to create a repor results in a [error][client][connection] Error: Parse Error error being spit out and the report just hangs there.

[timroes]

The same is true for PhantomJS. Tested on master, Chrome Linux.

[azasypkin]

It may be caused by #18951: I'm trying to figure that out at the moment.

[stacey-gammon]

Issue has to do with base path and new platform. Once #19261 is checked in we can add a test that verifies reporting works without the --no-base-path that would have caught this.