[MINOR][VL] Drop modify_arrow_dataset_scan_option.patch

[yaooqinn]

What changes were proposed in this pull request?

Drop ep/build-velox/src/modify_arrow_dataset_scan_option.patch and the two
shell call sites that apply / stage it:

• dev/build-arrow.sh — patch -p1 < .../modify_arrow_dataset_scan_option.patch
• ep/build-velox/src/get-velox.sh — cp + git add that copy the patch
  into the Velox source tree

Why are the changes needed?

The patch added a native CSV / dataset scan-option API
(CsvFragmentScanOptions::from, DeserializeMap, mapToExpressionLiteral, …)
that was originally consumed by Gluten's native Arrow CSV reader path.

That path is gone:

• [GLUTEN-11088][VL] Fall back CSV reader #11190 fell CSV back to vanilla Spark
• 0658e906f / 97f463813 / 9ea8290a / d206c5e20 removed the JVM-side
  callers, the ArrowUtil reader path, and the
  spark.gluten.sql.native.arrow.reader.enabled config

Nothing inside Gluten or Velox now references the symbols the patch
introduces, so it's dead code in the build. This PR is the final cleanup in
that chain.

How was this patch tested?

Local verification on Ubuntu 24.04 / x86_64:

• grep across the repo — 0 callers of CsvFragmentScanOptions,
  CsvFragmentScanOptions::from, DeserializeMap, mapToExpressionLiteral,
  createNative(... FragmentScanOptions), CsvConvertOptions,
  testCsvConvertOptions
• nm -C on freshly built libarrow_dataset.a (both java-dist and
  cpp-jni outputs) — none of the patch's symbols are present
• arrow_ep/cpp/src/arrow/dataset/file_csv.cc on disk is the unmodified
  upstream source — the patch was never applied with this change in place
• dev/buildbundle-veloxbe.sh --enable_vcpkg=ON → BUILD SUCCESS for all 5
  Spark profiles (3.3 / 3.4 / 3.5 / 4.0 / 4.1)
• spark-shell on the resulting bundle, reading a CSV file, prints
  GlutenFallbackReporter: Validation failed for plan: Scan csv , due to: Unsupported file format TextReadFormat and produces a vanilla
  FileScan csv physical plan — confirming CSV is fallback-by-design and
  never enters the native path the dropped patch fed.

Generated-by: Claude claude-opus-4.7

[philo-he]

Thanks for the PR. Just to confirm – will we permanently remove the arrow based CSV reader support? cc @jinchengchenghh, @FelixYBW

[FelixYBW]

Thanks for the PR. Just to confirm – will we permanently remove the arrow based CSV reader support? cc @jinchengchenghh, @FelixYBW

No, we may need to enable it later as it's required by one customer. If we decide to enable it, we will maintain the csv scan.

FYI, @zhouyuan

[philo-he]

If the Arrow-based CSV reader is still needed, can we introduce a build option to control whether these related patches are applied, and skip the Arrow Java build accordingly (use the official Arrow JAR from Maven Central instead)? If only a few users rely on it, perhaps we could disable it by default.

[yaooqinn]

Closing per @FelixYBW's note above — keeping the CSV scan scaffolding for the potential future customer use case. Thanks for the context!

[zhouyuan]

Thanks, we are now investigating on Velox CSV reader and it seems also have a gaps vs. Spark CSV reader

[FelixYBW]

Just noted the csv reader is already deleted in PR #12130

Let's clean up the patch as well.

[philo-he]

LGTM. Thanks. cc @zhouyuan

[prestodb-ci]

Rebase job