Fix BigModel stable diffusion pipeline (#19277)

### Description
Fix two issues:
(1) We can only use single quote inside `bash -c "..."`. Current
pipeline job stopped at `python3 demo_txt2img.py astronaut` and skip the
following commands. In this change, we remove the remaining commands to
get same effect (otherwise, the pipeline runtime might be 2 hours
instead of 15 minutes).
(2) Fix a typo of Stable.

tools/ci_build/github/azure-pipelines/bigmodels-ci-pipeline.yml

@@ -136,11 +136,11 @@ stages:
 
     - template: templates/explicitly-defined-final-tasks.yml
 
-- stage: Stale_Diffusion
+- stage: Stable_Diffusion
   dependsOn:
   - Build_Onnxruntime_Cuda
   jobs:
-  - job: Stale_Diffusion
+  - job: Stable_Diffusion
     variables:
       skipComponentGovernanceDetection: true
       CCACHE_DIR: $(Pipeline.Workspace)/ccache
@@ -171,12 +171,7 @@ stages:
             python3 -m pip install -r requirements-cuda11.txt; \
             python3 -m pip install --upgrade polygraphy onnx-graphsurgeon --extra-index-url https://pypi.ngc.nvidia.com; \
             echo Generate an image guided by a text prompt; \
-            python3 demo_txt2img.py "astronaut riding a horse on mars"; \
-            echo Generate an image with Stable Diffusion XL guided by a text prompt; \
-            python3 demo_txt2img_xl.py 'starry night over Golden Gate Bridge by van gogh'; \
-            python3 demo_txt2img_xl.py --enable-refiner 'starry night over Golden Gate Bridge by van gogh'; \
-            echo Generate an image guided by a text prompt using LCM LoRA; \
-            python3 demo_txt2img_xl.py --scheduler LCM --lora-weights latent-consistency/lcm-lora-sdxl --denoising-steps 4 "Self-portrait oil painting, a beautiful cyborg with golden hair, 8k"; \
+            python3 demo_txt2img.py 'astronaut riding a horse on mars'; \
             popd; \
           "
       displayName: 'Run stable diffusion demo'