Return Array.Empty instead of collection [] (#25137)

src/Microsoft.PowerShell.Commands.Management/commands/management/Process.cs

@@ -2692,7 +2692,7 @@ namespace Microsoft.PowerShell.Commands
             // -Verb is not supported on non-Windows platforms as well as Windows headless SKUs
             if (!Platform.IsWindowsDesktop)
             {
-                return [];
+                return Array.Empty<CompletionResult>();
             }
 
             // Completion: Start-Process -FilePath <path> -Verb <wordToComplete>
@@ -2726,7 +2726,7 @@ namespace Microsoft.PowerShell.Commands
                 }
             }
 
-            return [];
+            return Array.Empty<CompletionResult>();
         }
 
         /// <summary>