SDPA decode perf improvements for qwen-3.5-35B-A3B (#18759) #2336

Job	Run time
test-coreml / test-backend-macos (coreml, models) / macos-job	50m 38s
test-coreml / test-backend-macos (coreml, operators) / macos-job	50m 38s
test-coreml / test-backend-macos (coreml_static_int8, models) / macos-job	50m 38s
test-coreml / test-backend-linux	-1s
test-coreml / test-backend-macos (coreml_static_int8, operators) / macos-job	50m 38s
test-coreml / package-golden-artifacts	0s
	3h 22m 31s

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