MM-15288: Migrate CommandStore.Get to sync by default (#10739)

* MM-15288: Migrate Command.Get to sync by default

* addressing review comments, updating status code of err returned by Get Method

app/webhook.go

@@ -686,11 +686,9 @@ func (a *App) HandleCommandWebhook(hookId string, response *model.CommandRespons
 		hook = result.Data.(*model.CommandWebhook)
 	}
 
-	var cmd *model.Command
-	if result := <-a.Srv.Store.Command().Get(hook.CommandId); result.Err != nil {
-		return model.NewAppError("HandleCommandWebhook", "web.command_webhook.command.app_error", nil, "err="+result.Err.Message, http.StatusBadRequest)
-	} else {
-		cmd = result.Data.(*model.Command)
+	cmd, err := a.Srv.Store.Command().Get(hook.CommandId)
+	if err != nil {
+		return model.NewAppError("HandleCommandWebhook", "web.command_webhook.command.app_error", nil, "err="+err.Message, http.StatusBadRequest)
 	}
 
 	args := &model.CommandArgs{
@@ -705,6 +703,6 @@ func (a *App) HandleCommandWebhook(hookId string, response *model.CommandRespons
 		return model.NewAppError("HandleCommandWebhook", "web.command_webhook.invalid.app_error", nil, "err="+result.Err.Message, result.Err.StatusCode)
 	}
 
-	_, err := a.HandleCommandResponse(cmd, args, response, false)
+	_, err = a.HandleCommandResponse(cmd, args, response, false)
 	return err
 }