[MIRROR] Admin server announcement uses new announcement span [MDB IGNORE] (#25737)

* Admin server announcement uses new announcement span (#80403)

## About The Pull Request

The current admin announce is just notice span text, which is easily
missed mixed in with all the other white noise of the chat box.
Currently admins have to fill it with linebreaks or manually add their
own spans to increase visibility.

This updates the admin announcement proc to use the new alert box divs,
similar to other announcements, making it more visible.

## Why It's Good For The Game

Admin server-wide announcements are generally things you want the
players to notice

![image](https://github.com/tgstation/tgstation/assets/83487515/460bacbb-3a7f-4855-9e16-24b1533f61bd)

## Changelog

🆑 LT3
admin: Server wide admin announcements now use an alert box like other
announcements
/🆑

---------

Co-authored-by: MrMelbert <51863163+MrMelbert@ users.noreply.github.com>

* Admin server announcement uses new announcement span

---------

Co-authored-by: lessthanthree <83487515+lessthnthree@users.noreply.github.com>
Co-authored-by: MrMelbert <51863163+MrMelbert@ users.noreply.github.com>

code/modules/admin/verbs/admin.dm

@@ -37,7 +37,7 @@
 	if(message)
 		if(!check_rights(R_SERVER,0))
 			message = adminscrub(message,500)
-		to_chat(world, "[span_adminnotice("<b>[usr.client.holder.fakekey ? "Administrator" : usr.key] Announces:</b>")]\n \t [message]", confidential = TRUE)
+		send_formatted_announcement(message, "From [usr.client.holder.fakekey ? "Administrator" : usr.key]")
 		log_admin("Announce: [key_name(usr)] : [message]")
 	BLACKBOX_LOG_ADMIN_VERB("Announce")