fix: set `selector_result_cache_size` in unit test #19405

Job	Run time
Check (windows-2022)	16m 26s
Check (ubuntu-20.04)	10m 16s
Check License Header	2m 8s
Check typos and docs	10s
Build GreptimeDB binaries (ubuntu-20.04)	11m 32s
Toml Check	3m 18s
Build GreptimeDB binary (profile-CI) (ubuntu-20.04)	10m 54s
Clippy	10m 34s
coverage	18m 14s
Rustfmt	1m 21s
Unstable Fuzz Test (unstable_fuzz_create_table_standalone)	5m 3s
Fuzz Test (Distributed, Remote WAL, fuzz_create_table)	9m 35s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_migrate_mito_regions)	8m 58s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_failover_mito_regions)	8m 23s
Fuzz Test (Distributed, Remote WAL, fuzz_alter_table)	9m 4s
Fuzz Test (Distributed, Remote WAL, fuzz_create_database)	9m 50s
Fuzz Test with Chaos (Distributed, Remote WAL, fuzz_failover_metric_regions)	7m 40s
Fuzz Test (Distributed, Remote WAL, fuzz_create_logical_table)	9m 10s
Fuzz Test (Distributed, Remote WAL, fuzz_alter_logical_table)	8m 35s
Fuzz Test (Distributed, Remote WAL, fuzz_insert)	8m 44s
Fuzz Test (Distributed, Remote WAL, fuzz_insert_logical_table)	10m 2s
Sqlness Test (Basic)	2m 21s
Sqlness Test (Remote WAL)	2m 54s
Fuzz Test (fuzz_create_table)	7m 28s
Fuzz Test (fuzz_alter_table)	6m 32s
Fuzz Test (fuzz_create_database)	6m 18s
Fuzz Test (fuzz_create_logical_table)	6m 24s
Fuzz Test (fuzz_alter_logical_table)	7m 12s
Fuzz Test (fuzz_insert)	6m 12s
Fuzz Test (fuzz_insert_logical_table)	7m 39s
	3h 52m 57s

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