More accurate memory accounting in external sort

### Is your feature request related to a problem or challenge?

https://github.com/apache/datafusion/pull/14644 fixed an external sorting bug. Each batch's memory overhead is estimated as `2 * batch memory size` for the extra row conversion overhead. It works for common cases but still can fail. See https://github.com/apache/datafusion/pull/14644#issuecomment-2659063578 and https://github.com/apache/datafusion/pull/14644#issuecomment-2660783992.

To implement a more accurate memory size estimation for those edge cases, we can first do `col->row` conversion and measure the memory consumption. (depends on https://github.com/apache/datafusion/issues/7053)

### Describe the solution you'd like

_No response_

### Describe alternatives you've considered

_No response_

### Additional context

_No response_