perf(nns): Improve neuron validation batching (#3105) #21632

Job	Run time
Bazel Build Fuzzers	2m 43s
Bazel Test All	32m 42s
Bazel Test macOS Intel	59m 56s
Bazel Build All Config Check	0s
Bazel Build Fuzzers AFL	4m 46s
Build IC	16m 36s
Python CI Tests	2m 0s
Cargo Build Release Linux	23s
Cargo Clippy Linux	23s
Build Determinism (//publish/binaries:upload, release, build-ic/release, false)	32s
Build Determinism (//publish/canisters:upload, canisters, build-ic/canisters, false)	37s
Build Determinism (//ic-os/guestos/envs/prod:upload_disk-img, guest-os/update-img, build-ic/icos/...	32s
Build Determinism (//ic-os/hostos/envs/prod:upload_update-img, host-os/update-img, build-ic/icos/...	32s
Build Determinism (//ic-os/setupos/envs/prod:upload_disk-img, setup-os/disk-img, build-ic/icos/se...	37s
	2h 2m 19s

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