disable osx CI

the azure agent doesnt set DOTNET_ROOT and global tools doesnt work

ref https://github.com/Microsoft/azure-pipelines-image-generation/issues/531
ref https://github.com/dotnet/cli/issues/9114

Author: enricosada

azure-pipelines.yml

@@ -45,22 +45,3 @@ jobs:
       testResultsFormat: 'VSTest'
       testResultsFiles: 'tests/**/*.trx'
     condition: succeededOrFailed()
-- job: MacOS
-  pool:
-    vmImage: 'macOS-10.13'
-  steps:
-  - script: echo "##vso[task.setvariable variable=FrameworkPathOverride]$(dirname $(which mono))/../lib/mono/4.5/"
-    displayName: Workaround .NET reference assemblies on linux
-  - script: echo $(dirname $(which dotnet))
-    displayName: Display Workaround .NET Global Tool expect dotnet env var set
-  - script: echo "##vso[task.setvariable variable=DOTNET_ROOT]$(dirname $(which dotnet))"
-    displayName: Workaround .NET Global Tool expect dotnet env var set
-  - script: dotnet pack build.proj -v n
-    displayName: Create package
-  - script: dotnet test build.proj -v n
-    displayName: Run tests
-  - task: PublishTestResults@2
-    inputs:
-      testResultsFormat: 'VSTest'
-      testResultsFiles: 'tests/**/*.trx'
-    condition: succeededOrFailed()