refine information schema cache

[crazycs520]

Enhancement

workload: stale read, with tidb_read_staleness=-60;

 sysbench --config-file=sysbench.conf stale_read.lua --threads=20 --read_staleness=-60 --kv_read_timeout=100 --max_execution_time=400 --mysql-ignore-errors=all run

When TiDB domain load schema meets following error:

[2023/11/03 18:29:30.023 +08:00] [WARN] [domain.go:196] ["failed to get schema version"] [error="There is no Write MVCC info for the schema version"] [version=2410] [startTS=445384588003639307]

The QPS will droped cause by information schema cache is missed, then need to load snapshot information schema.

This is caused by information schema cache will be invalid since there is a schema version with schemaTs=0, then infoCache.GetBySnapshotTS will always return nil.

version: v6.5.5