Fix spacing in issue navbar (#30238) (#30242)

Backport #30238 by @silverwind

Create a new `issue-navbar` class specifically for this bar, previous
class used in many places and I thought I had them all removed, but not
this one.

Fixes: https://github.com/go-gitea/gitea/issues/30226

Co-authored-by: silverwind <me@silverwind.io>

templates/repo/issue/choose.tmpl

@@ -3,7 +3,7 @@
 	{{template "repo/header" .}}
 	<div class="ui container">
 		{{template "base/alert" .}}
-		<div class="navbar">
+		<div class="issue-navbar">
 			{{template "repo/issue/navbar" .}}
 		</div>
 		<div class="divider"></div>