Fix latejoin menu marine title (#5537)

# About the pull request
I realised the marine role category title was never fixed from the rank
rework rebranding Squad Marine to Squad Rifleman.
This fixes it.
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# Explain why it's good for the game
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# Changelog
:cl:
spellcheck: The latejoin menu marine category title is now Marines
instead of Squad Riflemen, as this was an inaccuracy.
/:cl:

code/modules/mob/new_player/new_player.dm

@@ -347,7 +347,7 @@
 			roles_show ^= FLAG_SHOW_MEDICAL
 
 		else if(roles_show & FLAG_SHOW_MARINES && GLOB.ROLES_MARINES.Find(J.title))
-			dat += "<hr>Squad Riflemen:<br>"
+			dat += "<hr>Marines:<br>"
 			roles_show ^= FLAG_SHOW_MARINES
 
 		dat += "<a href='byond://?src=\ref[src];lobby_choice=SelectedJob;job_selected=[J.title]'>[J.disp_title] ([J.current_positions]) (Active: [active])</a><br>"