Fix build break for #26873: Move enable_pix_capture parsing to WebGpuExecutionProviderConfig #7283

Job	Run time
5. Build Extended Minimal	10m 6s
2. Build Minimal (Exceptions Disabled)	9m 28s
6b. Build Minimal (No Optional Features)	7m 5s
6c. Build Extended Minimal (No Optional Features)	7m 35s
1. Build Full ORT and Generate ORT Files	17m 22s
6a. Build Regular (No Optional Features)	11m 27s
4. Build Minimal (Globally Allowed Types)	7m 59s
7. Build Extended Minimal (Android NNAPI)	8m 33s
3b. Build Minimal (Type Reduction)	8m 17s
3a. Build Minimal (Custom Ops)	8m 10s
	1h 36m 2s

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