Update .NET standalone activity examples to use IDs and task queue names in the code sample (#4516)

Co-authored-by: Milecia McG <47196133+flippedcoder@users.noreply.github.com>

Author: fretz12

docs/develop/dotnet/activities/standalone-activities.mdx

@@ -228,7 +228,7 @@ You can pass the Activity as either a lambda expression or a string Activity typ
 // Using a lambda expression (type-safe)
 var result = await client.ExecuteActivityAsync(
     () => MyActivities.ComposeGreetingAsync(new ComposeGreetingInput("Hello", "World")),
-    new("my-activity-id", "my-task-queue")
+    new("standalone-activity-id", "standalone-activity-sample")
     {
         ScheduleToCloseTimeout = TimeSpan.FromSeconds(10),
     });
@@ -237,7 +237,7 @@ var result = await client.ExecuteActivityAsync(
 var result = await client.ExecuteActivityAsync<string>(
     "ComposeGreeting",
     new object?[] { new ComposeGreetingInput("Hello", "World") },
-    new("my-activity-id", "my-task-queue")
+    new("standalone-activity-id", "standalone-activity-sample")
     {
         ScheduleToCloseTimeout = TimeSpan.FromSeconds(10),
     });