removes webgpu from onnxruntime-foundry-nuget package (#27929)

Required for Foundry Local which will download and install webgpu as a
plugin-ep

Co-authored-by: Prathik Rao <prathikrao@microsoft.com>

Author: prathikr

tools/ci_build/github/azure-pipelines/custom-nuget-packaging-pipeline.yml

@@ -97,7 +97,7 @@ extends:
           msbuildPlatform: x64
           packageName: x64-cuda
           CudaVersion: ${{ parameters.CudaVersion }}
-          buildparameter: --use_cuda --cuda_home=${{ variables.win_cuda_home }} --enable_onnx_tests --use_webgpu --nvcc_threads 1 --caller_framework WinAI --cmake_extra_defines "CMAKE_CUDA_ARCHITECTURES=${{ variables.CmakeCudaArchitectures }}"
+          buildparameter: --use_cuda --cuda_home=${{ variables.win_cuda_home }} --enable_onnx_tests --nvcc_threads 1 --caller_framework WinAI --cmake_extra_defines "CMAKE_CUDA_ARCHITECTURES=${{ variables.CmakeCudaArchitectures }}"
           runTests: false
           buildJava: false
           java_artifact_id: onnxruntime_gpu
@@ -129,7 +129,7 @@ extends:
       - template: templates/mac-cpu-packaging-pipeline.yml
         parameters:
           AllowReleasedOpsetOnly: 1
-          AdditionalBuildFlags: '--use_webgpu --skip_tests'
+          AdditionalBuildFlags: '--skip_tests'
           DoEsrp: true
 
       - template: templates/foundry-local-nuget-packaging.yml