Azure CI should fail on test failures

[alimcmaster1]

As per title I imagine this is something we would like?

This CI build seems to have status green on Azure despite the fact tests seem to be failing on MacOS-35, or am I missing something?

Issue found on this PR.

This seems to be related microsoft/azure-pipelines-tasks#1268.

[TomAugspurger]

From
microsoft/azure-pipelines-tasks#1268 (comment)

- powershell: |
    $junitXml = "junit/unit-test.xml"
    $(Get-Content $junitXml | Out-String) -match 'failures="(.*?)"'
    if ($matches[1] -eq 0)
    {
      Write-Host "No test failures"
    }
    else
    {
      # note that this will produce $LASTEXITCODE=1
      Write-Error "$($matches[1]) tests failed"
    }
  displayName: Check for test failures

we'd need to change that to test-data-single.xml and test-data-multi.xml and exit with a failure if either of those contain failures or errors.