CK: Remove 41 commented-out dead code blocks (~200 lines) (#6302)

Depends on #6300 

## Summary

Remove 41 commented-out code blocks across 33 files in Composable
Kernel, totaling ~200 lines.

Identified using an automated dead code scanning skill (`ck-dead-code`)
with a calibrated two-stage pipeline:
1. **Pre-filter**: Keyword-based scan found 1,338 `//`-commented blocks.
Calibrated heuristics (trained on 50-sample expert classification)
reduced to 89 high-confidence candidates — 93% noise reduction.
2. **Expert triage**: LLM expert classified each block in context as
CODE_REMOVE, CODE_KEEP, or NOT_CODE.

| Classification | Count |
|---------------|-------|
| Removed (this PR) | 41 |
| Kept (debug helpers, alt configs, reference impls) | 32 |
| Not code (false positives) | 16 |

Removed blocks include: superseded implementations, old test data,
abandoned stubs, unreachable code, and buggy dead code.

include/ck/problem_transform/transform_forward_convolution3d_into_gemm_v4r4r4_ndhwc_kzyxc_ndhwk.hpp

@@ -137,13 +137,6 @@ transform_forward_convolution3d_into_gemm_v4r4r4_ndhwc_kzyxc_ndhwk_pad(
         make_tuple(Sequence<0>{}, Sequence<1>{}),
         make_tuple(Sequence<0>{}, Sequence<1>{}));
 
-    // const auto out_grid_desc_gemmm_gemmn = transform_tensor_descriptor(
-    //     out_n_do_ho_wo_k_grid_desc,
-    //     make_tuple(make_merge_transform(make_tuple(N, Do, Ho, Wo)),
-    //                make_pass_through_transform(K)),
-    //     make_tuple(Sequence<0, 1, 2, 3>{}, Sequence<3>{}),
-    //     make_tuple(Sequence<0>{}, Sequence<1>{}));
-
     return make_tuple(in_grid_desc_gemmk0_gemmm_gemmk1,
                       wei_grid_desc_gemmk0_gemmn_gemmk1,
                       out_grid_desc_gemmm_gemmn);