GH-45656: [C#] Fix failing MacOS builds

[CurtHagenlocher]

Rationale for this change

Fix MacOS builds by removing command-line sourcelink tool. This appears to be deprecated and the certificate is expired.

Are there any user-facing changes?

No.

• GitHub Issue: [C#] C# builds are failing on MacOS #45656

[kou]

+1

Wow! sourcelink is deprecated!?
Can we remove this

arrow/dev/release/utils-create-release-tarball.sh

Lines 52 to 59 in 56436e8

	# Create a dummy .git/ directory to download the source files from GitHub with Source Link in C#.
	dummy_git=${root_folder}/csharp/dummy.git
	mkdir ${dummy_git}
	pushd ${dummy_git}
	echo ${release_hash} > HEAD
	echo "[remote \"origin\"] url = https://github.com/${GITHUB_REPOSITORY:-apache/arrow}.git" >> config
	mkdir objects refs
	popd

workaround for sourcelink?

[CurtHagenlocher]

+1

Wow! sourcelink is deprecated!? Can we remove this workaround for sourcelink?

Maybe?

It's the dotnet tool that's deprecated, at least according to its source site and the site for the package that replaces it. I don't know what this means for our release verification step, but a local build did seem to include all the right stuff in the form of the additional NuGet artifact and some bits in the PDB.

EDIT: This looks like it's for a source release. I don't know why the source link would be needed for a source release, as presumably someone who wants to build locally would not need to reference the GitHub sources. As I don't understand exactly what the script is supposed to achieve, I'm not going to remove those lines just yet as part of this PR.

[conbench-apache-arrow]

After merging your PR, Conbench analyzed the 4 benchmarking runs that have been run so far on merge-commit 19a67c7.

There were no benchmark performance regressions. 🎉

The full Conbench report has more details. It also includes information about 15 possible false positives for unstable benchmarks that are known to sometimes produce them.

[kou]

Ah, sourcelink command line is deprecated but Source Link itself is still used.

The csharp/dummy.git is used when we build .snuget (.pdb in .snuget) from source archive (not git clone-ed directory). Because https://github.com/dotnet/sourcelink refers .git/ to collect Git repository information. See also:

• [C#] Source Link doesn't work with the C# release script #21580 / ARROW-5092: [C#] Create a dummy .git directory to download the source files from GitHub with Source Link #4488
• Support repos with a direct reference specified in HEAD file dotnet/sourcelink#266

It seems that https://github.com/dotnet/sourcelink still does it. ( https://github.com/dotnet/sourcelink doesn't provide configuration items for repository name in GitHub such as apache/arrow.) So it seems that we can't remove the workaround...