incorrect column type when sync to starrocks

[jzhao20230918]

Version:

• Bifrost Version: [e.g. v1.6.0-beta.03]
  latest docker
• Os Version: [e.g. CentOS Linux release 7.7.1908]
• Browse: [e.g. Chrome]

Describe the bug

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To Reproduce

Steps to reproduce the behavior:

1. sync data from mysql to starrocks
2. choose create starrocks table on fly
3. the coloum type in mysql is varchar(300)
4. bifrost would try to create table in starrocks with column type char(300), since the size is > 255, error would be raised
5. even size is < 256, e.g. varchar(50), it would be converted to char(50) in starrocks

Expected behavior
varchar in mysql should be varchar in starrocks

A clear and concise description of what you expected to happen.

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Additional context

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