CI: pack C# NuGet overrides in Release

[rekhoff]

Description of Changes

CI now packs the local SpacetimeDB.BSATN.Runtime and SpacetimeDB.Runtime NuGet packages using the Release configuration in both the unity-testsuite and csharp-testsuite jobs.

This makes the NuGet override deterministic because sdks/csharp/tools~/write-nuget-config.sh points to crates/bindings-csharp/*/bin/Release, and dotnet pack otherwise defaults to Debug.

This is needed due to a CI failure occurring in #3982 in which the one of our smoketests fails because the resolved version of the package lacks RefOption<...>.GetListSerializer, resulting in a CS0117 error. Because this failure is not actually related of the changes in 3982, it is being pulled out into a separate PR.

API and ABI breaking changes

None.

Expected complexity level and risk

1 - Trivial

Testing

• Confirm CI pass

[bfops]

This makes the NuGet override deterministic because sdks/csharp/tools~/write-nuget-config.sh points to crates/bindings-csharp/*/bin/Release, and dotnet pack otherwise defaults to Debug.

I don't think that this is correct? When I run dotnet pack in a fresh dir, I only have a Release directory.

Apparently this wasn't always true:

If you're developing with the .NET 8 SDK or a later version, the command uses the Release configuration by default for projects whose TargetFramework is set to net8.0 or a later version. The default build configuration is Debug for earlier versions of the SDK and for earlier target frameworks.

(https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-pack#options)

Tests are run in fresh directories, so there shouldn't be any stale directories around. If this were building the wrong dir, I would expect tests to always get it blatantly wrong?

[bfops]

(I don't really have an objection to merging this, I'm just not sure that it will actually fix the issue you're experiencing?)

[rekhoff]

This makes the NuGet override deterministic because sdks/csharp/tools~/write-nuget-config.sh points to crates/bindings-csharp/*/bin/Release, and dotnet pack otherwise defaults to Debug.

I don't think that this is correct? When I run dotnet pack in a fresh dir, I only have a Release directory.

Apparently this wasn't always true:

If you're developing with the .NET 8 SDK or a later version, the command uses the Release configuration by default for projects whose TargetFramework is set to net8.0 or a later version. The default build configuration is Debug for earlier versions of the SDK and for earlier target frameworks.

(https://learn.microsoft.com/en-us/dotnet/core/tools/dotnet-pack#options)

Tests are run in fresh directories, so there shouldn't be any stale directories around. If this were building the wrong dir, I would expect tests to always get it blatantly wrong?

Fair enough, you're right. Well for what it's worth, I re-ran the job on 3982 and it passed this time. ¯\_(ツ)_/¯ Maybe it's not an issue, and this is unnecessary. This was an attempt to prevent flakiness by being explicit.