Revert new lobby ui. (#21494)

Reverts #20467

For some reason, if you put a png into icon() and then show that to a
client, it uses a colossal amount of GPU. No idea.

Reverts to our older lobby system pending TGUI update.

Fixes #21489

code/controllers/subsystems/initialization/atlas.dm

@@ -19,16 +19,6 @@ SUBSYSTEM_DEF(atlas)
 	var/datum/space_sector/current_sector
 	var/list/possible_sectors = list()
 
-	/// A list of icons used for the lobby image
-	var/list/icon/lobby_icons = list()
-
-	/**
-	 * Delay between lobby transitions, in deciseconds
-	 *
-	 * If set to 0, no transitions will be used
-	 */
-	var/lobby_transitions = 0
-
 	//Note that the dirs here are REVERSE because they're used for entry points, so it'd be the dir facing starboard for example.
 	//These are strings because otherwise the list indexes would be out of bounds. Thanks BYOND.
 	var/list/naval_to_dir = list(
@@ -224,24 +214,8 @@ SUBSYSTEM_DEF(atlas)
 
 	setup_spawnpoints()
 
-	setup_lobby_icons()
-
 	return SS_INIT_SUCCESS
 
-/datum/controller/subsystem/atlas/proc/setup_lobby_icons()
-	SHOULD_NOT_SLEEP(TRUE)
-
-	var/list/paths = current_sector.lobby_icon_image_paths || current_map.lobby_icon_image_paths
-
-	if(!length(paths))
-		stack_trace("No lobby icons found! Setup either the map or the sector ones!")
-		lobby_icons += icon('icons/misc/titlescreens/runtime/test.png')
-		return
-
-	var/random_path = pick(paths)
-	for(var/path in random_path)
-		lobby_icons += icon(path)
-
 /datum/controller/subsystem/atlas/proc/load_map_directory(directory, overwrite_default_z = FALSE)
 	. = 0
 	if (!directory)