[fix](tvf) Change the type of the `partition_key` column read by tvf to VARCHAR(65533)

[BePPPower]

Proposed changes

Issue Number: close #xxx

When using CTAS from TVF, if the partition_key used as partition column in the table creation, the partition column type cannot be STRING. So, we change the type of the partition_key column read by tvf to VARCHAR(65533)

Further comments

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