Fix sidebar label dropdown divider (go-gitea#25359)

Follow go-gitea#25312 

Also fix the label dropdown on sidebar

Before:

<img width="1345" alt="Screen Shot 2023-06-19 at 08 55 05"
src="https://github.com/go-gitea/gitea/assets/17645053/3a98e871-b482-4ecb-8ce2-74df67fb65a7">

After:

<img width="1408" alt="Screen Shot 2023-06-19 at 08 57 17"
src="https://github.com/go-gitea/gitea/assets/17645053/09af15cc-1250-49b3-98b6-5b1a2b9021cb">

web_src/js/features/repo-issue.js

@@ -149,7 +149,7 @@ export function initRepoIssueSidebarList() {
       }
     }
   });
-  $('.ui.dropdown.label-filter').dropdown('setting', {'hideDividers': 'empty'}).dropdown('refreshItems');
+  $('.ui.dropdown.label-filter, .ui.dropdown.select-label').dropdown('setting', {'hideDividers': 'empty'}).dropdown('refreshItems');
 }
 
 export function initRepoIssueCommentDelete() {