[SPARK-15223][DOCS] fix wrongly named config reference
[SPARK-15223][DOCS] fix wrongly named config reference

## What changes were proposed in this pull request?

The configuration setting `spark.executor.logs.rolling.size.maxBytes` was changed to `spark.executor.logs.rolling.maxSize` in 1.4 or so.

This commit fixes a remaining reference to the old name in the documentation.

Also the description for `spark.executor.logs.rolling.maxSize` was edited to clearly state that the unit for the size is bytes.

## How was this patch tested?

no tests

Author: Philipp Hoffmann <mail@philipphoffmann.de>

Closes #13001 from philipphoffmann/patch-3.

(cherry picked from commit 65b4ab281efd170c9fad7152629f68eaef7f7088)
Signed-off-by: Andrew Or <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@databricks.com>

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