Refactor: Extract type alias from examples #4271

Job	Run time
Build (nightly, bench,serde,bt,singlethreaded)	52s
stores (stores/memstore)	55s
stores (stores/rocksstore)	6m 23s
cluster-benchmark (cluster_benchmark)	49s
examples (stable, memstore)	47s
lint	11m 48s
examples (stable, raft-kv-memstore)	2m 40s
openraft-feature-test (nightly)	52s
examples (stable, raft-kv-memstore-grpc)	1m 3s
openraft-feature-test (nightly, serde)	52s
openraft-test (stable, 0)	3m 19s
examples (stable, raft-kv-memstore-network-v2)	1m 0s
openraft-feature-test (nightly, single-term-leader)	48s
openraft-test (nightly, 30)	3m 22s
examples (stable, raft-kv-memstore-opendal-snapshot-data)	1m 11s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	52s
openraft-test (nightly, 0, single-term-leader)	3m 18s
examples (stable, raft-kv-memstore-singlethreaded)	1m 7s
examples (stable, raft-kv-rocksdb)	8m 22s
openraft-test-bench (nightly)	1m 2s
examples (nightly, memstore)	57s
rt-monoio	41s
examples (nightly, raft-kv-memstore)	2m 21s
examples (nightly, raft-kv-memstore-grpc)	1m 5s
tests-feature-test (nightly)	2m 55s
tests-feature-test (nightly, single-term-leader)	3m 0s
examples (nightly, raft-kv-memstore-network-v2)	1m 14s
examples (nightly, raft-kv-memstore-opendal-snapshot-data)	1m 28s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 11s
examples (nightly, raft-kv-rocksdb)	12m 47s
	1h 19m 1s

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