Now we are nesting DefaultWALProvider inside RegionGroupingProvider, which makes the logic ambiguous since a "provider" itself should provide logs. Suggest to directly instantiate FSHlog in RegionGroupingProvider.
W.r.t wal group name, now in RegionGroupingProvider it's using sth like "<factoryId>-null-<randomUUID>" which is quite long and unnecessary. Suggest to directly use "<providerId>.<groupName>".
For more details, please refer to the initial patch.