[IcebergIO] Use InternalRecordWrapper partition util

[ahmedabu98]

Previously we were manually doing conversions to determine a record's partition. We recently found that Iceberg has existing public utils that do this; this change switches to use those utils.

Fixes #32865

[ahmedabu98]

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[svetakvsundhar]

for my knowledge, it's unclear to me how testIdentityPartitioning() was passing when identity should support Any source type. Is it worth adding an integration test to ensure just the Write works when partitioning by just date, as well as Any?

[ahmedabu98]

This test used to not include date and the other time types. This PR adds adds them to the test (your comment is actually positioned on the lines that add them).