qa/suites/rados/singleton/all: remove test_envlibrados_for_rocksdb

In rocksdb 7.0, all envlibrados files were moved to a separate repository (ref: facebook/rocksdb#9206).
The new repo is temporary and serves as an example before it is finalized where and who to host RADOS support.

Since this new repo is outside of the rocksdb repo and in an unceratin state, we should remove support for it in main
and Reef test suites. Quincy and below still use rocksdb 6.0, so the same does not apply.

Fixes: https://tracker.ceph.com/issues/59057
Signed-off-by: Laura Flores <[email protected]>

Author: ljflores