Fix measuring duration of processor and command (#3040)

I noticed this when i had my migration run for a long time and at the
end I wanted to know, how long it really took. The migration duration
was zero.

## Processor

Although the log outputs `Duration` of the processor activity, this is
always zero. Its because `Duration` is not dynamic – it does not return
real current duration. Its value is calculated and updated only when
`Stop()` is called.

## Command base

Basically the same problem as in `Processor`, but from the other side.
The activity is stopped immediately after it is started, so it reports
zero duration at the end. Even when the telemetry is disabled, there is
no need to not measure duration of the command. Because even wihout
telemetry, we want to see duration in the log outputs. And `Stop()`
basically does nothing just updates duration.

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Refactor**
* Enhanced activity lifecycle management within telemetry and processing
workflows.
  * Removed unused code dependencies.

* **Style**
  * Minor formatting improvements.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

Author: MrHinsh

src/MigrationTools.Host/Commands/CommandBase.cs

@@ -65,7 +65,6 @@ public sealed override async Task<int> ExecuteAsync(CommandContext context, TSet
                 {
                     Log.Debug("Disabling Telemetry {CommandName}", this.GetType().Name);
                     CommandActivity.AddTag("DisableTelemetry", settings.DisableTelemetry);
-                    CommandActivity.Stop();
                     ActivitySourceProvider.DisableActivitySource();
                 }
                 //Enable Debug Trace
@@ -105,7 +104,7 @@ public sealed override async Task<int> ExecuteAsync(CommandContext context, TSet
 
         internal virtual Task<int> ExecuteInternalAsync(CommandContext context, TSettings settings)
         {
-            return Task.FromResult( 0);
+            return Task.FromResult(0);
         }
 
         public void RunStartupLogic(TSettings settings)

src/MigrationTools/Processors/Infrastructure/Processor.cs

@@ -1,14 +1,11 @@
 using System;
 using System.Collections.Generic;
-using System.ComponentModel.Design;
 using System.Diagnostics;
 using System.Linq;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
-using MigrationTools._EngineV1.Configuration;
 using MigrationTools.Endpoints;
-using MigrationTools.Endpoints.Infrastructure;
 using MigrationTools.Enrichers;
 using MigrationTools.Exceptions;
 using MigrationTools.Services;
@@ -139,6 +136,7 @@ public void Execute()
                 }
                 finally
                 {
+                    ProcessorActivity.Stop();
                     Log.LogInformation("{ProcessorName} completed in {ProcessorDuration} ", Name, ProcessorActivity.Duration.ToString("c"));
                 }
 
@@ -172,4 +170,4 @@ protected static void AddParameter(string name, IDictionary<string, string> stor
             if (!store.ContainsKey(name)) store.Add(name, value);
         }
     }
-}
+}