Remove redundant code

source/Octopus.Tentacle/Kubernetes/Scripts/RunningKubernetesJob.cs

@@ -80,12 +80,14 @@ public async Task Execute()
             {
                 using var writer = ScriptLog.CreateWriter();
 
-                scriptCancellationToken.Register(() =>
+                //register a cancellation callback so that when the script is cancelled, we cancel the job
+                //we use a using to make sure this callback is deregistered
+                using var cancellationTokenRegistration = scriptCancellationToken.Register(() =>
                 {
                     writer.WriteOutput(ProcessOutputSource.StdOut, "Script execution canceled.");
                     writer.WriteVerbose($"Deleting Kubernetes Job '{jobName}'");
 
-                    //we spawn the job cancellation on a background thread
+                    //we spawn the job cancellation on a background thread (as this callback runs synchronously)
                     Task.Run(() => jobService.Delete(scriptTicket, CancellationToken.None), CancellationToken.None);
                 });
 
@@ -141,7 +143,6 @@ public async Task Execute()
         async Task<int> MonitorJobAndLogs(IScriptLogWriter writer)
         {
             var jobCompletionCancellationTokenSource = new CancellationTokenSource();
-
             var checkJobTask = CheckIfJobHasCompleted(jobCompletionCancellationTokenSource);
 
             //we pass the job completion CTS here because its used to cancel the writing of the job stream
@@ -313,12 +314,5 @@ void RecordScriptHasCompleted(int exitCode)
                 }
             }
         }
-
-
-        public async Task Cancel()
-        {
-            // The cancel cannot be cancelled (via cancellation token)
-            await jobService.Delete(scriptTicket, CancellationToken.None);
-        }
     }
 }

source/Octopus.Tentacle/Scripts/IRunningScript.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Threading.Tasks;
 using Octopus.Tentacle.Contracts;
 
 namespace Octopus.Tentacle.Scripts
@@ -9,6 +8,5 @@ public interface IRunningScript
         int ExitCode { get; }
         ProcessState State { get; }
         IScriptLog ScriptLog { get; }
-        Task Cancel();
     }
 }

source/Octopus.Tentacle/Scripts/RunningScript.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Threading;
-using System.Threading.Tasks;
 using Octopus.Diagnostics;
 using Octopus.Tentacle.Contracts;
 using Octopus.Tentacle.Util;
@@ -49,7 +48,6 @@ public RunningScript(IShell shell,
         public IScriptLog ScriptLog { get; }
 
         //Cancellation of the local shell is handled by the cancellation token supplied
-        public Task Cancel() => Task.CompletedTask;
 
         public void Execute()
         {

source/Octopus.Tentacle/Services/Scripts/ScriptServiceV3Alpha.cs

@@ -101,7 +101,7 @@ public async Task<ScriptStatusResponseV3Alpha> CancelScriptAsync(CancelScriptCom
         {
             if (runningScripts.TryGetValue(command.ScriptTicket, out var runningScript))
             {
-                await runningScript.Cancel();
+                runningScript.Cancel();
             }
 
             return await GetResponse(command.ScriptTicket, command.LastLogSequence, runningScript?.Process);
@@ -179,15 +179,9 @@ public RunningScriptWrapper(ScriptStateStore scriptStateStore)
 
             public CancellationToken CancellationToken { get; }
 
-            public async Task Cancel()
+            public void Cancel()
             {
                 cancellationTokenSource.Cancel();
-
-                //We don't want to just rel on the cancellation token performing the cancellation
-                //This is because the K8s Jobs need to be cancelled/deleted via an async API call
-                //and CancellationTokens cancellation registrations are synchronous callbacks
-                if (Process is not null)
-                    await Process.Cancel();
             }
 
             public void Dispose()