Tests: massively improve the memory leak test performance (#4568)

* Tests: massively improve the memory leak test performance

With the growing number of worlds, GC becomes the bottleneck and slows down the test.

* Tests: fix typing in general/test_memory

test/general/test_memory.py

@@ -1,5 +1,6 @@
 import unittest
 
+from BaseClasses import MultiWorld
 from worlds.AutoWorld import AutoWorldRegister
 from . import setup_solo_multiworld
 
@@ -9,8 +10,12 @@ class TestWorldMemory(unittest.TestCase):
         """Tests that worlds don't leak references to MultiWorld or themselves with default options."""
         import gc
         import weakref
+        refs: dict[str, weakref.ReferenceType[MultiWorld]] = {}
         for game_name, world_type in AutoWorldRegister.world_types.items():
-            with self.subTest("Game", game_name=game_name):
+            with self.subTest("Game creation", game_name=game_name):
                 weak = weakref.ref(setup_solo_multiworld(world_type))
-                gc.collect()
+                refs[game_name] = weak
+        gc.collect()
+        for game_name, weak in refs.items():
+            with self.subTest("Game cleanup", game_name=game_name):
                 self.assertFalse(weak(), "World leaked a reference")