Applying ACTool still times out with a 503 due to CDN not supporting streaming servlets

[kwin]

Despite the fix applied in the context of #801 the logging of long-running ACTool installation still does not work.
The issue is that the stream log GET servlet does not expose streaming behaviour (i.e. does not hit the client until it is complete).

Locally (i.e. without a CDN) it works just fine but in AEMaaCS where the request is issued from the Fastly CDN it seems that Fastly is waiting for the servlet to finish sending before passing it on to the requester.

Compare with https://docs.fastly.com/en/guides/streaming-miss

[kwin]

I asked about the Fastly feature "Streaming Miss" in https://experienceleague.adobe.com/home?support-tab=my-cases&case-id=E-001645423&org-id=FA907D44536A3C2B0A490D4D%40AdobeOrg#support.

[kwin]

Adobe confirmed that "Streaming miss" is not enabled, meaning that even with streaming servlets (i.e. ones sending some bytes within 60 seconds) one runs into a timeout on client side as the Fastly POP will always wait until the origin has sent the full response before delivering to the client.