Add llm_methods metadata to multimethod PTE export #30278

Job	Run time
gather-models	7s
test-models-linux (buck2, mv3, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	10m 21s
test-models-linux (buck2, mv3, portable, linux.2xlarge, 90) / linux-job	9m 23s
test-models-linux (cmake, vit, portable, linux.2xlarge, 90) / linux-job	16m 33s
test-models-linux (cmake, vit, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	10m 18s
test-models-linux (cmake, mv3, portable, linux.2xlarge, 90) / linux-job	9m 21s
test-models-linux (cmake, mv3, xnnpack-quantization-delegation, linux.2xlarge, 90) / linux-job	9m 48s
	1h 5m 51s

Provide feedback