Making method ExecuteAsync virtual. (#16496)

Co-authored-by: Kvyatkovsky, Petr <pkvyatkovsky@qulix.com>
(cherry picked from commit 3a9ef38)

src/Umbraco.Infrastructure/HostedServices/RecurringHostedServiceBase.cs

@@ -129,7 +129,7 @@ public virtual Task StopAsync(CancellationToken cancellationToken)
     ///     Executes the task.
     /// </summary>
     /// <param name="state">The task state.</param>
-    public async void ExecuteAsync(object? state)
+    public virtual async void ExecuteAsync(object? state)
     {
         try
         {