Fix XNN PreLU use after free #1560

Job	Run time
test-arm / test-backend-linux (arm_tosa_fp, models) / linux-job	25m 55s
test-arm / test-backend-linux (arm_tosa_fp, operators) / linux-job	18m 17s
test-arm / test-backend-linux (arm_vgf_fp, operators) / linux-job	16m 58s
test-arm / test-backend-linux (arm_vgf_fp, models) / linux-job	26m 0s
test-arm / test-backend-macos	0s
test-arm / package-golden-artifacts	42s
	1h 27m 52s

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