[mysql] newly add table stuck after several splits

[yujiaxinlong]

Describe the bug(Please use English)
A clear and concise description of what the bug is.

Environment :

• Flink version : 1.13.6
• Flink CDC version: 2.3-SNAPSHOT
• Database and version: mysql 5.7.35

To Reproduce
Steps to reproduce the behavior:

1. Thes test data :
   two tables A and B.
   firstly only read table A until snapshot read finished, then add table B. , table A and B both have continuous binlog
2. The test code :
   use DataStream API , source reader parallism set to 1, simply read and print
3. The error :
   the snapshot read of table B get stucked after read several splits, the last split seems just won't finish.