fix: type conversion error

[menshibin]

Description

The taosBenchmark writes bigint, bigint unsigned, and int unsigned fields, all of which are truncated to int.

jiar: https://jira.taosdata.com:18080/browse/TD-37666

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?

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