Agent: Use spawn context for LDAP server process

Forked processes will inherit all resources from the parent process.
This includes the socket we use for ensuring only a single agent is
running at any given time. Additionaly, threads will also be inherited
by the forked process, which could cause problems.

Using a spawn context should fix our singleton issue, and give the
process a cleaner environment in which to run.

Issue #2820

monkey/infection_monkey/exploit/log4shell_utils/ldap_server.py

@@ -94,7 +94,7 @@ def __init__(
         :param storage_dir: A directory where the LDAP server can safely store files it needs during
                             runtime.
         """
-        self._reactor_startup_completed = multiprocessing.Event()
+        self._reactor_startup_completed = multiprocessing.get_context("spawn").Event()
         self._ldap_server_port = ldap_server_port
         self._http_server_ip = http_server_ip
         self._http_server_port = http_server_port
@@ -114,7 +114,7 @@ def run(self):
         # has been stopped. To work around this, the reactor is configured and run in a separate
         # process. This allows us to run multiple LDAP servers sequentially or simultaneously and
         # stop each one when we're done with it.
-        self._server_process = multiprocessing.Process(
+        self._server_process = multiprocessing.get_context("spawn").Process(
             name=f"{threading.current_thread()}-LDAPServer-{insecure_generate_random_string(n=8)}",
             target=self._run_twisted_reactor,
             daemon=True,