This PR removes raft-ann-bench from the conda packages, build system, and documentation. This removal was previously announced for the 24.12 release in #2448.

Authors:
  - Corey J. Nolet (https://github.com/cjnolet)
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - Ben Frederickson (https://github.com/benfred)
  - Bradley Dice (https://github.com/bdice)

URL: #2497

We are keeping random ball cover headers in RAFT for 24.12, and random ball cover depends on distances and brute-force. Because of this, we're going to leave all of the VSS headers in RAFT for the time being, and will remove them all in a future PR once RBC is formally migrated to cuVS. The tests, benchmarks, and instantiations for all of these APIs will be removed, though, so while the actual headers can still be used, they are no longer being tested and could fail without warning. 

I've also included a note to users in the README about this, stating to use at their own risk.

Authors:
  - Corey J. Nolet (https://github.com/cjnolet)
  - Bradley Dice (https://github.com/bdice)

Approvers:
  - Ben Frederickson (https://github.com/benfred)
  - Bradley Dice (https://github.com/bdice)

URL: #2498