Add _ENABLE_VGF toggle to test targets #29972

Job	Run time
gather-models	10s
test-models-linux (cmake, mv3, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	9m 34s
test-models-linux (cmake, mv3, portable, linux.2xlarge, 90) / linux-job	9m 14s
test-models-linux (cmake, vit, portable, linux.2xlarge, 90) / linux-job	16m 20s
test-models-linux (cmake, vit, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	10m 13s
test-models-linux (buck2, mv3, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	10m 1s
test-models-linux (buck2, mv3, portable, linux.2xlarge, 90) / linux-job	9m 9s
	1h 4m 41s

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