[Core] fix QKV fusion for attention (#8829)
* start debugging the problem,
* start
* fix
* fix
* fix imports.
* handle hunyuan
* remove residuals.
* add a check for making sure there's appropriate procs.
* add more rigor to the tests.
* fix test
* remove redundant check
* fix-copies
* move check_qkv_fusion_matches_attn_procs_length and check_qkv_fusion_processors_exist.
