Refactor: Extract type alias from examples #4273

Job	Run time
openraft-test-bench (nightly)	1m 3s
openraft-test (stable, 0)	3m 34s
stores (stores/memstore)	58s
openraft-test (nightly, 30)	3m 43s
stores (stores/rocksstore)	6m 18s
openraft-test (nightly, 0, single-term-leader)	3m 13s
cluster-benchmark (cluster_benchmark)	1m 2s
lint	12m 7s
openraft-feature-test (nightly)	1m 0s
rt-monoio	51s
openraft-feature-test (nightly, serde)	1m 3s
openraft-feature-test (nightly, single-term-leader)	1m 3s
Build (nightly, bench,serde,bt,singlethreaded)	1m 2s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	1m 4s
tests-feature-test (nightly)	3m 14s
tests-feature-test (nightly, single-term-leader)	3m 9s
examples (stable, memstore)	40s
examples (stable, raft-kv-memstore)	2m 33s
examples (stable, raft-kv-memstore-grpc)	1m 47s
examples (stable, raft-kv-memstore-network-v2)	55s
examples (stable, raft-kv-memstore-opendal-snapshot-data)	1m 8s
examples (stable, raft-kv-memstore-singlethreaded)	54s
examples (stable, raft-kv-rocksdb)	8m 28s
examples (nightly, memstore)	1m 1s
examples (nightly, raft-kv-memstore)	2m 22s
examples (nightly, raft-kv-memstore-grpc)	1m 42s
examples (nightly, raft-kv-memstore-network-v2)	1m 12s
examples (nightly, raft-kv-memstore-opendal-snapshot-data)	1m 26s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 17s
examples (nightly, raft-kv-rocksdb)	12m 27s
	1h 22m 16s

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