Merge MSBuild functions in tools.ps1/sh

[ViktorHofer]

... and remove the InitializeToolset call from the functions by calling the nuget cache export function directly.

The GetNuGetPackageCachePath function all doesn't need a IF CI condition as the function is also unconditionally called in eng/common/build.ps1/sh.

The MSBuild-Core function is not used by anyone aside from the entry point in the VMR which I will update with the next re-bootstrap (just remove the -Core part from the function call).

Also remove a set of env vars that are already the default in NuGet now.

To double check:

• The right tests are in and the right validation has happened. Guidance: https://github.com/dotnet/arcade/blob/main/Documentation/Validation.md

[Copilot]

Pull request overview

Refactors the MSBuild helper in eng/common/tools.ps1 and eng/common/tools.sh by collapsing the previous MSBuild + MSBuild-Core wrapper pair into a single MSBuild function, dropping the InitializeToolset call that the wrapper used to make, and instead invoking GetNuGetPackageCachePath once at script-load time so the NuGet package cache environment variables are still exported.

Changes:

• Merged MSBuild and MSBuild-Core into a single function in both tools.ps1 and tools.sh, removing the InitializeToolset call previously triggered from MSBuild.
• Reordered tools.ps1 so DotNet and Enable-Nuget-EnhancedRetry are now defined alongside the other helpers rather than after the script's bottom initialization block.
• Added a top-level GetNuGetPackageCachePath invocation at the end of both scripts to ensure NUGET_PACKAGES is still exported even though InitializeToolset is no longer implicitly run by MSBuild.

Show a summary per file

File	Description
eng/common/tools.ps1	Merges MSBuild/MSBuild-Core, relocates DotNet and Enable-Nuget-EnhancedRetry, and calls GetNuGetPackageCachePath at script-load.
eng/common/tools.sh	Merges MSBuild/MSBuild-Core and calls GetNuGetPackageCachePath at script-load.

Note: eng/common is mirrored from Arcade, so making these changes in dotnet/arcade is correct. The behavioral change to export NUGET_PACKAGES at script source time (rather than lazily on first InitializeToolset call) affects every consumer that sources tools.ps1/tools.sh, including scripts that never invoke MSBuild; this widens blast radius beyond the MSBuild callers.

Copilot's findings

• Files reviewed: 2/2 changed files
• Comments generated: 0

[Copilot]

Copilot's findings

Comments suppressed due to low confidence (1)

eng/common/tools.sh:513

• The bash MSBuild previously exported NUGET_PLUGIN_HANDSHAKE_TIMEOUT_IN_SECONDS=20 and NUGET_PLUGIN_REQUEST_TIMEOUT_IN_SECONDS=20 (and Write-PipelineSetVariable'd them) whenever running under CI. The merged function no longer does that, and the values are not set anywhere else in eng/common. This is a behavior change that isn't called out in the PR description; if the intent is to drop these, please mention it, otherwise restore them inside the new if [[ "$ci" == true ]] block to keep parity with the previous behavior (and with the PowerShell side once it's also restored).

function MSBuild {
  if [[ "$ci" == true ]]; then
    if [[ "$binary_log" != true && "$exclude_ci_binary_log" != true ]]; then
      Write-PipelineTelemetryError -category 'Build'  "Binary log must be enabled in CI build, or explicitly opted-out from with the -noBinaryLog switch."
      ExitWithExitCode 1
    fi

    if [[ "$node_reuse" == true ]]; then
      Write-PipelineTelemetryError -category 'Build'  "Node reuse must be disabled in CI build."
      ExitWithExitCode 1
    fi
  fi

• Files reviewed: 2/2 changed files
• Comments generated: 1