Refactor: use type alias to simplify types #3317

Job	Run time
Build (nightly, bench,serde,bt,singlethreaded)	48s
openraft-test (stable, 0)	3m 14s
openraft-test (nightly, 30)	3m 30s
openraft-test (nightly, 0, single-term-leader)	3m 32s
cluster-benchmark (cluster_benchmark)	46s
examples (stable, memstore)	43s
lint	6m 19s
examples (stable, raft-kv-memstore)	2m 18s
examples (stable, raft-kv-memstore-generic-snapshot-data)	57s
openraft-feature-test (nightly)	48s
examples (stable, raft-kv-memstore-opendal-snapshot-data)	1m 29s
openraft-test-bench (nightly)	52s
openraft-feature-test (nightly, serde)	53s
examples (stable, raft-kv-memstore-singlethreaded)	59s
openraft-feature-test (nightly, single-term-leader)	51s
examples (stable, raft-kv-rocksdb)	7m 54s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	51s
stores (stores/memstore)	52s
examples (nightly, memstore)	1m 21s
stores (stores/rocksstore)	6m 2s
examples (nightly, raft-kv-memstore)	2m 12s
stores (stores/sledstore)	1m 5s
tests-feature-test (nightly)	3m 0s
examples (nightly, raft-kv-memstore-generic-snapshot-data)	1m 16s
tests-feature-test (nightly, single-term-leader)	3m 17s
examples (nightly, raft-kv-memstore-opendal-snapshot-data)	1m 53s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 23s
tests-feature-test (nightly, loosen-follower-log-revert)	3m 5s
examples (nightly, raft-kv-rocksdb)	12m 24s
	1h 14m 34s

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