The default values of shard_row_id_bits and pre_split_regions should be configurable #55716
Description
Feature Request
Is your feature request related to a problem? Please describe:
The default values of shard_row_id_bits and pre_split_regions are 0, which make the customers have to set it one by one on their table schemas.
Describe the feature you'd like:
Make the default values of shard_row_id_bits and pre_split_regions be configurable.
Describe alternatives you've considered:
No.
Teachability, Documentation, Adoption, Migration Strategy:
When a new customer want to migrate his database to TiDB, we nearly always suggest them to set shard_row_id_bits and pre_split_regions on their tables, make the default values configurable will make the migration easier.