Use flags for create post (#28857)

* Use flags for create post

* Remove unintended file

* Fix unintended change and types

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/webhook.go

@@ -365,7 +365,7 @@ func (a *App) CreateWebhookPost(c request.CTX, userID string, channel *model.Cha
 	}
 
 	for _, split := range splits {
-		if _, err = a.CreatePost(c, split, channel, false, false); err != nil {
+		if _, err = a.CreatePost(c, split, channel, model.CreatePostFlags{}); err != nil {
 			return nil, model.NewAppError("CreateWebhookPost", "api.post.create_webhook_post.creating.app_error", nil, "err="+err.Message, http.StatusInternalServerError)
 		}
 	}