[INLONG-6842][Sort] Improve mysql-cdc2.0 to support tables without primary key

[EMsnap]

Prepare a Pull Request

• Fixes [Improve] improve mysql-cdc2.0 to support faster snapshot read  #6842

Motivation

Fixes #6842

Modifications

A minor modification and improvemnt for Dblog : https://netflixtechblog.com/dblog-a-generic-change-data-capture-framework-69351fb9099b

1、remove the constraint in mysql-cdc 2.0 for primary key
2、for those tables which don't contain primary key, split the whole table as a chunk during split stage
3、since there's no need for the MySqlSourceEnumerator to upsert binlog with the snapshot data for a whole table
split , just let the highwatermark equals to the lowwatermark to escape the upsert stage.

Verifying this change

run AllmigrateTest

Documentation

• Does this pull request introduce a new feature? (yes / no)
• If yes, how is the feature documented? (not applicable / docs / JavaDocs / not documented)
• If a feature is not applicable for documentation, explain why?
• If a feature is not documented yet in this PR, please create a follow-up issue for adding the documentation

[gong]

manager need to modify. Because manager set scan.incremental.snapshot.enabled param.

[EMsnap]

manager need to modify. Because manager set scan.incremental.snapshot.enabled param.

will submit another pr for manager modification