tests: try to make s2n_mem_usage_test more useful #9392

Job	Run time
asan-unit-tests	4m 35s
clippy	10m 26s
fips (ubuntu-latest)	9m 25s
generate (ubuntu-latest)	14m 25s
fips (macOS-latest)	11m 13s
generate (macOS-latest)	14m 17s
generate-openssl-102	9m 16s
harness-interop-tests	5m 8s
minimal-versions (bindings/rust/extended)	5m 44s
minimal-versions (bindings/rust/standard)	4m 32s
msrv	3s
pcaps	5m 16s
rustfmt	3m 55s
s2n-tls-binding-examples	3m 48s
check-generated-cargo-toml	3m 36s
	1h 45m 39s

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