Remove agent.os demands on windows ci (dotnet#621)

* Remove agent.os demands as this queue has only Windows_NT machines

* Bump parallel to 4

* Set parallel to 99 per PR feedback

Author: safern

.vsts-dotnet-ci.yml

@@ -11,5 +11,3 @@ phases:
     buildScript: build.cmd
     queue:
       name: Hosted VS2017
-      demands:
-        - agent.os -equals Windows_NT

build/ci/phase-template.yml

@@ -13,12 +13,12 @@ phases:
       ${{ if ne(parameters.dockerImage, '') }}:
         _PREVIEW_VSTS_DOCKER_IMAGE: ${{ parameters.dockerImage }}
     queue:
-      parallel: 2
+      parallel: 99
       matrix:
         Build_Debug:
           _configuration: Debug
         Build_Release:
-          _configuration: Release 
+          _configuration: Release
       ${{ insert }}: ${{ parameters.queue }}
     steps:
     - script: $(_buildScript) -$(_configuration) -runtests