[Tools] Fix the issue of processing empty list in CI pipeline. (#14263)

* Add Debug info for test phase

* Fix the issue of test project list is empty

Co-authored-by: wyunchi-ms <yunwang@microsoft.com>

build.proj

@@ -144,7 +144,7 @@
         Value="@(TestCsprojList->Split(`;`)->Count())">
         <Output
             TaskParameter="Value"
-            PropertyName="IsTestListEmpty" />
+            PropertyName="TestCsprojListCount" />
     </CreateProperty>
   </Target>
 
@@ -317,7 +317,7 @@
 
     <!-- https://github.com/Microsoft/msbuild/issues/3157#issuecomment-378002971 -->
     <!-- https://github.com/xunit/xunit/issues/1154#issuecomment-405366373 -->
-    <Exec Command="dotnet test $(RepoArtifacts)Azure.PowerShell.sln --filter &quot;AcceptanceType=CheckIn%26RunType!=DesktopOnly&quot; --configuration $(Configuration) --framework $(TestFramework) --logger trx --results-directory &quot;$(TestOutputDirectory)&quot;" Condition="'$(IsTestListEmpty)' == 'false'" />
+    <Exec Command="dotnet test $(RepoArtifacts)Azure.PowerShell.sln --filter &quot;AcceptanceType=CheckIn%26RunType!=DesktopOnly&quot; --configuration $(Configuration) --framework $(TestFramework) --logger trx --results-directory &quot;$(TestOutputDirectory)&quot;" Condition="$(TestCsprojListCount) == 0" />
     <Message Importance="high" Text="Finish running tests..." />
     <OnError ExecuteTargets="TestFailureErrorMessage" />
   </Target>