Add icon to buttons "Close with Comment", "Close Pull Request", "Close Issue" (#36654)

Newbies often use the "Close with Comments" button instead of deleting
their comment. Icon should prevent mis-clicks.

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Co-authored-by: Yuriy.Khlynovskiy <yuriy.khlynovskiy@incomsystem.ru>
Co-authored-by: silverwind <me@silverwind.io>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

web_src/css/base.css

@@ -1095,7 +1095,6 @@ table th[data-sortt-desc] .svg {
 }
 
 .btn,
-.ui.ui.button,
 .ui.ui.dropdown,
 .flex-text-inline,
 .flex-text-inline > a,