Refactor: delete async-trait, fix typo, use tokio to replace async_std #24

Job	Run time
Build (nightly, bench,serde,bt,singlethreaded)	53s
stores (memstore)	43s
stores (rocksstore)	5m 58s
stores (rocksstore-compat07)	6m 7s
stores (sledstore)	51s
cluster-benchmark (cluster_benchmark)	46s
examples (stable, raft-kv-memstore)	2m 11s
examples (stable, raft-kv-memstore-singlethreaded)	58s
examples (stable, raft-kv-rocksdb)	6m 35s
external-stores (stores/rocksstore-v2)	5m 55s
lint	6m 29s
examples (nightly, raft-kv-memstore)	2m 10s
examples (nightly, raft-kv-memstore-singlethreaded)	1m 17s
openraft-feature-test (nightly)	46s
openraft-test (stable, 0)	3m 1s
examples (nightly, raft-kv-rocksdb)	6m 23s
openraft-feature-test (nightly, serde)	48s
openraft-test (nightly, 30)	3m 16s
openraft-feature-test (nightly, single-term-leader)	52s
openraft-test (nightly, 0, single-term-leader)	3m 7s
openraft-feature-test (nightly, single-term-leader,serde,singlethreaded)	48s
openraft-test-bench (nightly)	53s
tests-feature-test (nightly)	2m 46s
tests-feature-test (nightly, single-term-leader)	2m 44s
tests-feature-test (nightly, loosen-follower-log-revert)	2m 43s
	1h 9m 0s

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