feat(nns): Move neuron validation to timer (#3181) #617

Job	Run time
Bazel System Test Hotfix	21m 31s
Bazel System Test Staging	16m 26s
Bazel System Test Nightly	35m 49s
Dependency Scan for Release	4m 5s
Setting up guest os qualification pipeline	7s
CI Main / Bazel Test All	17m 10s
CI Main / Bazel Test macOS Intel	48m 13s
CI Main / Bazel Build All Config Check	0s
CI Main / Bazel Build Fuzzers	2m 25s
CI Main / Bazel Build Fuzzers AFL	5m 16s
CI Main / Cargo Build Release Linux	31s
CI Main / Build IC	16m 46s
CI Main / Cargo Clippy Linux	26s
CI Main / Python CI Tests	1m 59s
Qualifying d9fe2076f677a08734bed90c67b1c3f4056ed621 -> bdb7c71b590e33040fa721eac1936ab108a65a96	1h 29m 11s
CI Main / Build Determinism	0s
	4h 19m 55s

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