Remove unused MemoryReactor changes now that we don't have a test to use it

tests/server.py

@@ -777,20 +777,6 @@ class ThreadPool:
     See twisted.python.threadpool.ThreadPool
     """
 
-    min = 1
-    """
-    "minimum number of threads in the pool"
-
-    This is a "threadless" thread pool, so we always have one thread.
-    """
-
-    max = 1
-    """
-    "maximum number of threads in the pool"
-
-    This is a "threadless" thread pool, so we always have one thread.
-    """
-
     def __init__(self, reactor: IReactorTime):
         self._reactor = reactor