cleanup http pipelining code

[AiraYumi]

Remove the http pipeline code.

• Compiling Viewer
• Remove http pipeline code.
• Check Login
• Check that the objects are displayed
• Confirm that teleportation is possible
• Check that messages are sent and received

[RyeMutt]

HTTP Pipelining is utilized for mesh and texture fetch as those are large assets that benefit from pipelined downloads.

[AiraYumi]

Should we prioritize adding ways to speed up asset retrieval, such as HTTP/2 support, before removing the HTTP pipelining?

We believe it is necessary to implement an alternative process as soon as possible in order to update the unsupported openssl and curl as soon as possible.

[Quinn-Elara]

I've been pushing LL to work on HTTP/2 support for a little while now, last discussion I had on it was in the SUG meeting last week.

Person to bug on the issue is Monty Linden, as really this work needs to happen ASAP as these old libs are a serious security concern, as well as fixing some stalls in the asset pipeline caused by pipelining.

Summary of what was said (taken from the modemworld.me blog)

There is no current work on HTTP/2 for CDN and asset fetching. This is described as something LL want to get to, but keeps getting stalled due to the focus being on other areas of work. Monty Linden also noted a move to HTTP/2 may not yield any significant loading improvement over HTTP/1

Video of the meeting: https://youtu.be/RwdeOwdPWgY?si=QKr95VH8i7nxeyPP&t=843
(Conversation on HTTP/2 lasts about 15 mins, although happens between other conversations, but look for what Rider and Monty are saying).

[github-actions]

This pull request is stale because it has been open 30 days with no activity. Remove stale label or comment or it will be closed in 7 days

[AiraYumi]

I will close this as I will not be working on it until the work related to #3101 is completed.