Remove FP8 Z-Image quality artifacts

Signed-off-by: WeiQing Chen <david6666666@users.noreply.github.com>

tests/diffusion/quantization/artifacts/fp8_z_image_quality/README.md

@@ -1,46 +0,0 @@
-# FP8 Z-Image Quality Artifact
-
-Generated by:
-
-```bash
-CUDA_VISIBLE_DEVICES=0 \
-VLLM_OMNI_QUALITY_OUTPUT_DIR=$PWD/tests/diffusion/quantization/artifacts/fp8_z_image_quality \
-.venv/bin/python -m pytest \
-  tests/diffusion/quantization/test_quantization_quality.py::test_quantization_quality[fp8_z_image] \
-  -s -v -m ""
-```
-
-Quantized config:
-
-```python
-{
-    "method": "fp8",
-    "ignored_layers": [
-        "img_mlp",
-        "layers.15..29.{attention.to_qkv,attention.to_out.0,feed_forward.w13,feed_forward.w2}",
-        "model.layers.28..35.{self_attn.q_proj,self_attn.k_proj,self_attn.v_proj,self_attn.o_proj,"
-        "mlp.gate_proj,mlp.up_proj,mlp.down_proj}",
-    ],
-}
-```
-
-Result: passed with `max_lpips=0.15`.
-
-| Metric | Value |
-|--------|-------|
-| LPIPS | 0.128773 |
-| PSNR | 20.125577 dB |
-| MAE | 0.047712 |
-
-This uses regular online FP8 quantization for the text encoder, with only the final
-8 text-encoder blocks routed through `ignored_layers` for BF16 fallback.
-
-## Comparison
-
-![BF16 baseline vs FP8 quantized](fp8_z_image_comparison.png)
-
-## Individual Outputs
-
-![BF16 baseline](fp8_z_image_baseline.png)
-
-![FP8 quantized](fp8_z_image_quantized.png)