Only run Windows PowerShell 5.1 tests on CI with powershell.exe

Author: andyleejordan

PowerShellEditorServices.build.ps1

@@ -176,7 +176,9 @@ Task Test TestServer, TestE2E
 
 Task TestServer TestServerWinPS, TestServerPS7, TestServerPS72
 
-Task TestServerWinPS -If (-not $script:IsNix) Build, SetupHelpForTests, {
+# NOTE: While these can run under `pwsh.exe` we only want them to run under
+# `powershell.exe` so that the CI time isn't doubled.
+Task TestServerWinPS -If ($PSVersionTable.PSEdition -eq "Desktop") Build, SetupHelpForTests, {
     Set-Location .\test\PowerShellEditorServices.Test\
     # TODO: See https://github.com/dotnet/sdk/issues/18353 for x64 test host
     # that is debuggable! If architecture is added, the assembly path gets an
@@ -185,12 +187,12 @@ Task TestServerWinPS -If (-not $script:IsNix) Build, SetupHelpForTests, {
     Exec { & dotnet $script:dotnetTestArgs $script:NetRuntime.Desktop }
 }
 
-Task TestServerPS7 -If (-not $script:IsAppleM1 -and -not $script:IsArm64) Build, SetupHelpForTests, {
+Task TestServerPS7 -If ($PSVersionTable.PSEdition -eq "Core" -and -not $script:IsAppleM1 -and -not $script:IsArm64) Build, SetupHelpForTests, {
     Set-Location .\test\PowerShellEditorServices.Test\
     Exec { & dotnet $script:dotnetTestArgs $script:NetRuntime.PS7 }
 }
 
-Task TestServerPS72 Build, SetupHelpForTests, {
+Task TestServerPS72 -If ($PSVersionTable.PSEdition -eq "Core") Build, SetupHelpForTests, {
     Set-Location .\test\PowerShellEditorServices.Test\
     Exec { & dotnet $script:dotnetTestArgs $script:NetRuntime.PS72 }
 }