Update the logic to force cleanup all edit monitor instances.

Instead of checking the pidfiles, query all the running process with
binary ends with "edit_monitor" and kill all of those processes. This
ensures that if there are any unexpected edit monitor instances running
(e.g. due to b/382135550), the force cleanup can kill those processes as
well.

Bug: 382135550
Test: atest daemon_manager_test
Change-Id: I299f16b7b913e4ee470b5fe9ef0ffdad8d3c0945
diff --git a/tools/edit_monitor/daemon_manager_test.py b/tools/edit_monitor/daemon_manager_test.py
index 350739d..e412ab0 100644
--- a/tools/edit_monitor/daemon_manager_test.py
+++ b/tools/edit_monitor/daemon_manager_test.py
@@ -367,6 +367,26 @@
         fake_cclient, edit_event_pb2.EditEvent.FAILED_TO_REBOOT_EDIT_MONITOR
     )
 
+  @mock.patch('subprocess.check_output')
+  def test_cleanup_success(self, mock_check_output):
+    p = self._create_fake_deamon_process()
+    fake_cclient = FakeClearcutClient()
+    mock_check_output.return_value = f'user {p.pid} 1 1 1 1 1 edit_monitor arg'
+
+    dm = daemon_manager.DaemonManager(
+        TEST_BINARY_FILE,
+        daemon_target=long_running_daemon,
+        cclient=fake_cclient,
+    )
+    dm.cleanup()
+
+    self.assertFalse(p.is_alive())
+    self.assertTrue(
+        pathlib.Path(self.working_dir.name)
+        .joinpath(daemon_manager.BLOCK_SIGN_FILE)
+        .exists()
+    )
+
   def assert_run_simple_daemon_success(self):
     damone_output_file = tempfile.NamedTemporaryFile(
         dir=self.working_dir.name, delete=False