[copilot] setup .github/workflows/copilot-setup-steps.yml

[Copilot]

Context: https://docs.github.com/en/copilot/customizing-copilot/customizing-the-development-environment-for-copilot-coding-agent

Setup .github/workflows/copilot-setup-steps.yml, which is a Github action
that runs (only on Ubuntu) prior to Copilot doing its work.

This makes Copilot more useful, as it has a locally cloned and built source tree
with all dependencies installed. Copilot will be able to run various commands
to achieve tasks as assigned.

Other changes:

• Ignore errors from <GitCommitsInRange/>

Copilot must keep some custom git history, as this command was failing during our build:

> git log ^cfa4209..HEAD --oneline
fatal: bad revision '^cfa4209..HEAD'

We can ignore the error, and just use 0 for the commit range if this occurs.

• Our android-deps workload for provisioning Mono, can simply use:

"android-deps": { "extends" : [ "microsoft-net-runtime-android" ] }

Previously, it was failing to install a non-existent pack on Linux:

Installing pack Microsoft.NETCore.App.Runtime.AOT.linux-x64.Cross.android-x86 version 10.0.0-preview.6.25304.106...

[jonathanpeppers]

Previously, this was installing microsoft-net-runtime-android-aot:

Installing pack Microsoft.NETCore.App.Runtime.AOT.linux-x64.Cross.android-x86 version 10.0.0-preview.6.25304.106...

Which failed on Github actions on linux.

I think we only need "microsoft-net-runtime-android" here.

[jonathanpeppers]

A successful GitHub action run here:

• https://github.com/dotnet/android/actions/runs/15620287801

[jonathanpeppers]

@copilot check the changes again

[Copilot]

@copilot check the changes again

I've reviewed the current changes. The copilot-setup-steps.yml workflow has been successfully streamlined according to your feedback:

✅ Changed .NET version from 10.x to 9.x
✅ Removed the .NET verification step
✅ Removed basic dependencies installation
✅ Removed environment variables setup
✅ Removed external git dependencies preparation
✅ Removed NuGet package creation step
✅ Removed workload verification step
✅ Removed sample project build step
✅ Removed disk usage display
✅ Removed build artifacts display

The workflow now only contains the essential steps: checkout, setup .NET 9.x, run jenkins build, and upload logs on failure.

The ConfigureLocalWorkload.targets file correctly uses only "microsoft-net-runtime-android" for Linux to avoid the AOT installation failures.

The GitCommitsInRange tasks have ContinueOnError="true" to handle git history issues gracefully.

All requested changes have been implemented. (55fa5ff)