Refine selftest further #495

Job	Run time
examples_basic	41s
examples_ntt_kyber_dilithium_helium_core	2m 39s
Dry Run (slothy.targets.arm_v7m.cortex_m7)	39s
examples_ntt_kyber_dilithium_neon_core	22m 0s
Dry Run (slothy.targets.arm_v81m.cortex_m55r1)	3m 21s
fft	7m 36s
sqmag	57s
Dry Run (slothy.targets.arm_v81m.cortex_m85r1)	2m 8s
tutorial	13m 49s
Dry Run (slothy.targets.aarch64.cortex_a55)	9m 46s
Dry Run (slothy.targets.aarch64.cortex_a72_frontend)	37m 50s
Dry Run (slothy.targets.aarch64.apple_m1_firestorm_experimental)	28m 22s
Dry Run (slothy.targets.aarch64.apple_m1_icestorm_experimental)	24m 35s
	2h 34m 23s

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