[Native WebGPU] Exclude WebGPU EP from ConvFp16 3D tests. (microsoft#24327)

### Description
Exclude WebGPU from Conv3D tests 



### Motivation and Context
Fix failing tests in packaging pipelines.

Author: satyajandhyala

onnxruntime/test/providers/cpu/nn/conv_fp16_test.cc

@@ -518,7 +518,7 @@ TEST(ConvFp16Test, Conv3D_1) {
       vector<int64_t>{1, 1, 1},           // kernel_shape
       vector<int64_t>{0, 0, 0, 0, 0, 0},  // pads
       vector<int64_t>{1, 1, 1},           // strides
-      {}                                  // excluded EPs
+      {kWebGpuExecutionProvider}          // excluded EPs
   };
 
   vector<MLFloat16> X = {
@@ -557,7 +557,7 @@ TEST(ConvFp16Test, Conv3D_2) {
       vector<int64_t>{1, 1, 1},           // kernel_shape
       vector<int64_t>{2, 2, 2, 2, 2, 2},  // pads
       vector<int64_t>{2, 2, 2},           // strides
-      {}                                  // excluded EPs
+      {kWebGpuExecutionProvider}          // excluded EPs
   };
 
   vector<MLFloat16> X = {
@@ -601,7 +601,7 @@ TEST(ConvFp16Test, Conv3D_Bias) {
       vector<int64_t>{2, 2, 2},           // kernel_shape
       vector<int64_t>{2, 2, 2, 2, 2, 2},  // pads
       vector<int64_t>{2, 2, 2},           // strides
-      {}                                  // excluded EPs
+      {kWebGpuExecutionProvider}          // excluded EPs
   };
 
   vector<MLFloat16> X = {
@@ -1082,7 +1082,7 @@ TEST(ConvFp16Test, Pointwise_3D) {
       vector<int64_t>{1, 1, 1},           // kernel_shape
       vector<int64_t>{0, 0, 0, 0, 0, 0},  // pads
       vector<int64_t>{1, 1, 1},           // strides
-      {}                                  // excluded EPs
+      {kWebGpuExecutionProvider}          // excluded EPs
   };
 
   vector<MLFloat16> X = {