[Docs] Remove section about converting Delta back to parquet (#4117)

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#### Which Delta project/connector is this regarding?
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- [ ] Spark
- [ ] Standalone
- [ ] Flink
- [ ] Kernel
- [x] Other (docs)

## Description

Remove the section about "easily converting Delta to parquet" from the
docs. This section is very misleading as this doesn't work with anything
but the most trivial of Delta tables with no parquet-incompatible
features enabled. For the majority of modern Delta tables, the only real
option to achieve this is via CTAS or equivalent that rewrites the
contents as parquet, rather than an in-place conversion.

## How was this patch tested?

n/a

## Does this PR introduce _any_ user-facing changes?

Yes, the docs look different^^

docs/source/delta-utility.md

@@ -516,13 +516,6 @@ CONVERT TO DELTA iceberg.`<path-to-table>` NO STATISTICS
 
   - Converting Iceberg merge-on-read tables that have experienced updates, deletions, or merges is not supported.
 
-## Convert a Delta table to a Parquet table
-
-You can easily convert a Delta table back to a Parquet table using the following steps:
-
-1. If you have performed <Delta> operations that can change the data files (for example, `delete` or `merge`), run [vacuum](#delta-vacuum) with retention of 0 hours to delete all data files that do not belong to the latest version of the table.
-#. Delete the `_delta_log` directory in the table directory.
-
 <a id="restore-delta-table"></a>
 
 ## Restore a Delta table to an earlier state