(build) remove dotnet install step, it's already installed

Author: arturcic

build/tmpl/jobs.yml

@@ -6,12 +6,6 @@ jobs:
   pool:
     vmImage: ${{ parameters.vmImage }}
   steps:
-  - task: DotNetCoreInstaller@0
-    condition: eq( variables['Agent.OS'], 'Darwin' )
-    displayName: 'Use .NET Core sdk 2.x'
-    inputs:
-      version: '2.2.107'
-      packageType: sdk
   - task: UseRubyVersion@0
     condition: ne( variables['Agent.OS'], 'Darwin' )
     displayName: 'Use .Ruby >= 2.5'