Migrate Windows CLI validation to Hex1b-based E2E tests

## Description

Hex1b now supports Windows (as of v0.126.0). The CLI E2E tests (Aspire.Cli.EndToEnd.Tests) currently only run on Linux because Hex1b previously required a Linux terminal environment. A separate PowerShell-based starter validation script (ng/scripts/cli-starter-validation.ps1) was added in PR #15455 to provide basic Windows CLI coverage without Hex1b.

Now that Hex1b supports Windows, we should:

1. Enable Aspire.Cli.EndToEnd.Tests to run on Windows in CI (update RunOnGithubActionsWindows and related properties in the csproj)
2. Validate that the existing Hex1b-based tests pass on Windows runners
3. Consider retiring the PowerShell starter validation script once Windows Hex1b test coverage is sufficient

### Context

- Hex1b Windows support landed in v0.126.0 (updated in PR #16025)
- The csproj currently has — this is no longer true
- The starter validation script has a tight 15-minute job timeout on ARM64 runners, which causes intermittent timeouts

### References

- PR #15455 — Added Windows CLI starter validation (PowerShell-based workaround)
- PR #15599 — Added ARM64 to the starter validation matrix
- PR #16025 — Updated Hex1b to 0.126.0