Fix edit topic UI (#27925)
Before:
desktop view:
![image](https://github.com/go-gitea/gitea/assets/18380374/c04d8730-5dac-4318-9643-72801da0ca16)
mobile view:
![image](https://github.com/go-gitea/gitea/assets/18380374/187220d3-1fcc-4db8-9cf8-ee88fe92d989)
after click `Save` btn:
![image](https://github.com/go-gitea/gitea/assets/18380374/c3242470-7e6f-4ddc-a2ac-d896bbd39529)
![image](https://github.com/go-gitea/gitea/assets/18380374/82e03ba5-a6d2-4437-b074-387e7ad5b6ba)
refresh the page, you will see that `gt-m-0` is missing after save
topic:
![image](https://github.com/go-gitea/gitea/assets/18380374/26914820-9363-483c-af70-78b76de47523)
After:
desktop view:
![image](https://github.com/go-gitea/gitea/assets/18380374/12d878e1-351e-4983-b3d9-5216e9f30a19)
mobile view:
![image](https://github.com/go-gitea/gitea/assets/18380374/4adf9b0f-977b-4bbc-a42f-b9bfb2d648dd)
after click `Save` btn:
![image](https://github.com/go-gitea/gitea/assets/18380374/064c911e-d074-4432-8a55-8ff8ddb93989)