[DOC] Add rebase mode notes for databricks doc [skip ci]

[viadea]

Add rebase mode notes for databricks doc.

By default, those 2 parameters are LEGACY in Databricks(at least 9.1ML and 10.4ML).

 spark.sql.legacy.parquet.datetimeRebaseModeInWrite
 spark.sql.legacy.parquet.int96RebaseModeInWrite

If we are writing a parquet file with date/timestamp/int96, below fallback will happen:

!Output <InsertIntoHadoopFsRelationCommand> cannot run on GPU because LEGACY rebase mode for dates and timestamps is not supported; LEGACY rebase mode for int96 timestamps is not supported

Minimum repro is:

import scala.collection.Seq
import java.sql.Date
Seq(java.sql.Timestamp.valueOf("1500-01-01 00:00:00")).toDF("ts").write.format("parquet").mode("overwrite").save("/tmp/testparquet_legacy")

We need to manually set them back to "EXCEPTION" which is default value in Apache Spark.

[jlowe]

build