What problem does this PR solve?

Issue Number: ref #9722

Problem Summary:

• Introduce a struct RegionTableSize which is shared by a Table and all its related Regions. Once registered, a region will update its memory change to this struct, so the table would learn.
• Introduce maybeWarnMemoryLimitByTable and resetWarnMemoryLimitByTable, to log when the memory of a table goes beyond threshold.

Both of the systems works under the path that:

• When a region is created, either for prehandling or inserting, it would register it to RegionTable, and get its shared RegionTableSize.
• Ever since, the insert/delete from the Region would also reflect on this shared RegionTableSize.
• After an insertion, if the memory consumed by a table associated with the given region is reported to go beyond the threshold propotion, and the total memory used is also beyond the given memory limit(which is a very corner case), then we will issue a log.
• Afterwards, if the memory usage somehow goes upper, we don't print the log again for the same table.
• If the memory goes down by committing txns, or applying snapshots, we will reset the warning. So if the table still consumes much memory, a new log will be printed.
• If the region is splitted or merged, the table's memory usage is not affected. If the region is destroyed, the table's memory would be decresed.

Also:

• Remove some useless structures in RegionTable.
• Make safe ts related codes into SafeTsMgr.
• Rename some methods in Region to reflect what they actually do.

What is changed and how it works?

Record table-wise memory usage and warn when it goes beyond threshold

Check List

Tests

• Unit test
• Integration test
• Manual test (add detailed scripts or steps below)
• No code

Side effects

• Performance regression: Consumes more CPU
• Performance regression: Consumes more Memory
• Breaking backward compatibility

Documentation

• Affects user behaviors
• Contains syntax changes
• Contains variable changes
• Contains experimental features
• Changes MySQL compatibility

Release note

Add logging when the uncommitted in-memory data of a table reach a threshold