Consolidate ExcludeFromSourceBuild logic

Author: John Luo

Directory.Build.props

@@ -36,11 +36,6 @@
         '$(IsTestAssetProject)' == 'true' OR
         '$(IsBenchmarkProject)' == 'true' OR
         '$(IsUnitTestProject)' == 'true'">false</IsShipping>
-    <ExcludeFromSourceBuild Condition="'$(IsSampleProject)' == 'true' OR
-        '$(IsTestAssetProject)' == 'true' OR
-        '$(IsBenchmarkProject)' == 'true' OR
-        '$(IsUnitTestProject)' == 'true' OR
-        '$(IsSpecificationTestProject)' == 'true'">true</ExcludeFromSourceBuild>
 
     <!--
       Following logic mimics core-setup approach as well as

Directory.Build.targets

@@ -4,7 +4,15 @@
     <!-- Only build Microsoft.AspNetCore.App and ref/ assemblies in source build. -->
     <!-- Analyzer package are needed in source build for WebSDK -->
     <ExcludeFromSourceBuild
-        Condition="'$(ExcludeFromSourceBuild)' == '' and '$(DotNetBuildFromSource)' == 'true' and '$(IsAspNetCoreApp)' != 'true' and '$(IsAnalyzersProject)' != 'true'">true</ExcludeFromSourceBuild>
+        Condition="'$(ExcludeFromSourceBuild)' == '' and
+        '$(DotNetBuildFromSource)' == 'true' and
+        '$(IsAspNetCoreApp)' != 'true' and
+        '$(IsAnalyzersProject)' != 'true' and
+        ('$(IsSampleProject)' == 'true' OR
+         '$(IsTestAssetProject)' == 'true' OR
+         '$(IsBenchmarkProject)' == 'true' OR
+         '$(IsUnitTestProject)' == 'true' OR
+         '$(IsSpecificationTestProject)' == 'true')">true</ExcludeFromSourceBuild>
 
     <!-- If the user has specified that they want to skip building any test related projects with SkipTestBuild,
      suppress all targets for TestProjects using ExcludeFromBuild. -->