fix: failed to adapt varchar type to different data sources

[menshibin]

Description

Please briefly describe the code changes in this pull request.

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 66.66667% with 6 lines in your changes missing coverage. Please review.

Project coverage is 79.91%. Comparing base (6af0485) to head (b529b0d).

Files with missing lines	Patch %	Lines
...flink/cdc/serializable/RowDataCdcDeserializer.java	20.00%	3 Missing and 1 partial ⚠️
...a/flink/sink/serializer/RowDataSerializerBase.java	85.71%	0 Missing and 1 partial ⚠️
...e/serializable/TDengineRowDataDeserialization.java	83.33%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main      #14      +/-   ##
============================================
- Coverage     80.09%   79.91%   -0.19%     
- Complexity      484      485       +1     
============================================
  Files            56       56              
  Lines          2035     2046      +11     
  Branches        232      235       +3     
============================================
+ Hits           1630     1635       +5     
- Misses          287      290       +3     
- Partials        118      121       +3     

Flag	Coverage Δ
unittests	79.91% <66.66%> (-0.19%)	⬇️

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