grandpa: Ensure `WarpProof` stays in its limits #8593

Job	Run time
preflight / preflight	41s
preflight / ci-versions	1m 11s
test-full-crypto-feature	2m 27s
cargo-check-benches (master)	20m 49s
test-frame-ui	27m 1s
cargo-check-benches (current)	23m 11s
cargo-check-all-crate-macos	11m 14s
cargo-check-each-crate (1)	16m 9s
cargo-check-each-crate (2)	17m 24s
cargo-check-each-crate (3)	7m 25s
test-node-metrics	10m 19s
cargo-check-each-crate (4)	15m 2s
cargo-check-each-crate (5)	22m 51s
cargo-check-each-crate (6)	13m 0s
cargo-check-each-crate (7)	26m 20s
test-frame-examples-compile-to-wasm	3m 0s
test-deterministic-wasm	6m 11s
check-tracing	2m 16s
check-metadata-hash	5m 56s
node-bench-regression-guard	13s
All test misc tests passed	1s
	3h 52m 41s

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