hyper: drop support

lib : remove all hyper code
configure: stop detecting hyper
docs: no more mention of hyper
tests: mo more special-handling of hyper builds
CI: no jobs using hyper

Closes #15120

docs/DEPRECATE.md

@@ -23,36 +23,6 @@ and use TLS 1.3, or else it is not good enough.
 As of May 2024, the libraries that need to get fixed to remain supported after
 May 2025 are: BearSSL and Secure Transport.
 
-## Hyper
-
-Hyper is an alternative HTTP backend for curl. It uses the hyper library and
-could in theory be used for HTTP/1, HTTP/2 and even HTTP/3 in the future with
-curl.
-
-The original plan and goal was that we would add this HTTP alternative (using
-a memory-safe library) and that users could eventually build and use libcurl
-exactly as previously but with parts of the core being more memory-safe.
-
-The hyper implementation ran into some snags and 10-15 tests and HTTP/2
-support have remained disabled with hyper. For these reasons, hyper support
-has remained tagged EXPERIMENTAL.
-
-It is undoubtedly hard work to fix these remaining problems, as they typically
-require both rust and C knowledge in addition to deep HTTP familiarity. There
-does not seem to be that many persons interested or available for this
-challenge. Meanwhile, there is little if any demand for hyper from existing
-(lib)curl users.
-
-Finally: having support for hyper in curl has a significant cost: we need to
-maintain and develop a lot of functionality and tests twice to make sure
-libcurl works identically using either HTTP backend.
-
-The only way to keep hyper support in curl is to give it a good polish by
-someone with time, skill and energy to spend on this task.
-
-Unless a significant overhaul has proven to be in progress, hyper support is
-removed from curl in January 2025.
-
 ## Past removals
 
  - Pipelining
@@ -65,3 +35,4 @@ removed from curl in January 2025.
  - MinGW v1
  - NTLM_WB
  - space-separated `NOPROXY` patterns
+ - hyper