feat(wal): increase recovery parallelism (#4689) #22

Job	Run time
Build GreptimeDB binaries (ubuntu-20.04)	10m 52s
Build GreptimeDB binary (profile-CI) (ubuntu-20.04)	10m 51s
Check (windows-2022)	16m 36s
Check (ubuntu-20.04)	9m 35s
Check typos and docs	5s
Clippy	10m 22s
coverage	1s
Rustfmt	1m 48s
Check License Header	2m 13s
Toml Check	3m 27s
Unstable Fuzz Test (unstable_fuzz_create_table_standalone)	9m 41s
Fuzz Test (Distributed, Remote WAL, fuzz_create_table)	13m 21s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_migrate_mito_regions)	11m 53s
Fuzz Test (Distributed, Remote WAL, fuzz_alter_table)	12m 30s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_failover_mito_regions)	12m 49s
Fuzz Test (Distributed, Remote WAL, fuzz_create_database)	12m 25s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_failover_metric_regions)	12m 53s
Fuzz Test (Distributed, Remote WAL, fuzz_create_logical_table)	12m 2s
Fuzz Test (Distributed, Remote WAL, fuzz_alter_logical_table)	12m 31s
Fuzz Test (Distributed, Remote WAL, fuzz_insert)	12m 51s
Fuzz Test (Distributed, Remote WAL, fuzz_insert_logical_table)	12m 8s
Sqlness Test (Basic)	2m 31s
Fuzz Test (fuzz_create_table)	8m 47s
Sqlness Test (Remote WAL)	2m 49s
Fuzz Test (fuzz_alter_table)	9m 2s
Fuzz Test (fuzz_create_database)	9m 40s
Fuzz Test (fuzz_create_logical_table)	8m 54s
Fuzz Test (fuzz_alter_logical_table)	8m 54s
Fuzz Test (fuzz_insert)	8m 56s
Fuzz Test (fuzz_insert_logical_table)	9m 11s
	4h 29m 38s

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