Fix double border in system status table (#31363)

Fix regression from https://github.com/go-gitea/gitea/pull/30712 where
the introduction of this `<div>` caused the `.ui.attached:not(.message)
+ .ui.attached.segment:not(.top)` CSS selector to no longer work and
cause a double border.

Before:

<img width="200" alt="Screenshot 2024-06-13 at 19 06 12"
src="https://github.com/go-gitea/gitea/assets/115237/a9fa0688-adf0-4b2d-a958-6a7679a62031">

After:
<img width="232" alt="Screenshot 2024-06-13 at 19 05 57"
src="https://github.com/go-gitea/gitea/assets/115237/025b780f-f72f-4049-86de-a5d84851bd1d">

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/admin/dashboard.tmpl

@@ -76,9 +76,11 @@
 			{{ctx.Locale.Tr "admin.dashboard.system_status"}}
 		</h4>
 		{{/* TODO: make these stats work in multi-server deployments, likely needs per-server stats in DB */}}
+		<div class="ui attached table segment">
 			<div class="no-loading-indicator tw-hidden"></div>
-		<div hx-get="{{$.Link}}/system_status" hx-swap="morph:innerHTML" hx-trigger="every 5s" hx-indicator=".no-loading-indicator" class="ui attached table segment">
+			<div hx-get="{{$.Link}}/system_status" hx-swap="morph:innerHTML" hx-trigger="every 5s" hx-indicator=".no-loading-indicator">
 				{{template "admin/system_status" .}}
 			</div>
 		</div>
+	</div>
 {{template "admin/layout_footer" .}}