fix: Trim whitespace from CHAR types

[peasee]

🗣 Description

Trims whitespace from the end of CHAR datatypes when converting records to RecordBatch

This follows existing behavior from PostgreSQL:

Trailing spaces are removed when converting a character value to one of the other string types.

MySQL:

When CHAR values are retrieved, trailing spaces are removed unless the PAD_CHAR_TO_FULL_LENGTH SQL mode is enabled.

And arrow conversion in datafusion-table-providers

🔨 Related Issues

• Part of https://github.com/spiceai/spiceai/issues/1910