!temporary! Minimize use of unlike Helix queues

- eliminate OSX queue usage
- only target Linux queues in the "Tests: Helix ARM64 matrix" job that builds on Linux

Author: dougbu

eng/targets/Helix.Common.props

@@ -1,27 +1,26 @@
 <Project>
+  <Import Project="../Common.props" Condition=" '$(TargetOsName)' == '' " />
+
   <!-- this file is shared between Helix.proj and .csproj files -->
   <ItemGroup Condition="'$(IsWindowsOnlyTest)' != 'true'">
-    <HelixAvailablePlatform Include="Windows" />
-    <HelixAvailablePlatform Include="OSX" />
-    <HelixAvailablePlatform Include="Linux" />
+    <HelixAvailablePlatform Include="Windows" Condition=" '$(TargetOsName)' == 'win' " />
+    <HelixAvailablePlatform Include="Linux" Condition=" '$(TargetOsName)' == 'linux' " />
   </ItemGroup>
 
   <ItemGroup Condition="'$(IsWindowsOnlyTest)' == 'true'">
-    <HelixAvailablePlatform Include="Windows" />
+    <HelixAvailablePlatform Include="Windows" Condition=" '$(TargetOsName)' == 'win' " />
   </ItemGroup>
 
   <!-- PR(ci.yaml) required queues -->
   <ItemGroup Condition="'$(IsRequiredCheck)' == 'true' AND '$(TargetArchitecture)' == 'x64' AND '$(_UseHelixOpenQueues)' == 'true'">
     <HelixAvailableTargetQueue Include="Ubuntu.1804.Amd64.Open" Platform="Linux" />
     <HelixAvailableTargetQueue Include="Windows.10.Amd64.Server20H2.Open" Platform="Windows" />
-    <HelixAvailableTargetQueue Include="OSX.1014.Amd64.Open" Platform="Linux" />
   </ItemGroup>
 
   <!-- queues for helix-matrix.yml pipeline -->
   <ItemGroup Condition="'$(TargetArchitecture)' == 'x64' AND '$(IsHelixDaily)' == 'true' AND '$(_UseHelixOpenQueues)' == 'true' AND '$(IsWindowsOnlyTest)' != 'true'">
     <HelixAvailableTargetQueue Include="Ubuntu.1604.Amd64.Open" Platform="Linux" />
     <HelixAvailableTargetQueue Include="Ubuntu.2004.Amd64.Open" Platform="Linux" />
-    <HelixAvailableTargetQueue Include="OSX.1100.Amd64.Open" Platform="Linux" />
     <HelixAvailableTargetQueue Include="Debian.9.Amd64.Open" Platform="Linux" />
     <HelixAvailableTargetQueue Include="Redhat.7.Amd64.Open" Platform="Linux" />
     <HelixAvailableTargetQueue Include="(Fedora.33.Amd64.Open)[email protected]/dotnet-buildtools/prereqs:fedora-33-helix-20210120000908-a9df267" Platform="Linux" />