fix(logs): failures name their job, VM and user; the new VM form shows a list it could not load

- A failed cancel hook logged "worker task cancel failed": it now names
  the job, its kind, resource and user, with the traceback for a fault
  of the panel.
- novncd logged "Console connection failed" without the VM or the user.
- django-axes wrote four INFO lines a login ("Reset 0 access
  attempts"...); logins are on the Logs page, so it logs warnings only.
- The new VM form's machine types and disk buses answered 200 with an
  empty object when libvirt failed, and nothing was logged: the list
  stayed empty, the form could not go on and said nothing. They answer
  400 with the error, as the pool's volume list does, the warning is
  logged with the compute, and the form's lists show an error they get
  with the page's messages.

console/tests/test_novncd.py

@@ -17,6 +17,7 @@ from django.core.signing import TimestampSigner
 from django.conf import settings
 from django.test import TestCase, override_settings
 from instances.models import Instance
+from libvirt import libvirtError
 from console.tests.daemons import novncd_mod
 
 ROOT = Path(__file__).resolve().parent.parent.parent
@@ -63,6 +64,31 @@ class NovncdDaemonLogicTestCase(TestCase):
         self.assertEqual(opts.host, "192.168.1.100")
         self.assertEqual(opts.port, 7070)
 
+    @patch.object(novncd_mod, "get_connection_infos")
+    def test_a_console_that_cannot_be_reached_is_logged_with_its_vm_and_user(self, mock_get_info):
+        mock_get_info.side_effect = libvirtError("Domain not found")
+        self.authorize.return_value[0].name = "vm-alpha"
+        handler = self.ConsoleClient()
+        handler.path = "/novncd/?token=1-uuid"
+        with self.assertLogs(level="WARNING") as logs:
+            handler._new_client(socket_factory=MagicMock())
+        self.assertEqual(logs.output, ["WARNING:root:Console connection to VM vm-alpha for vnc-user failed: Domain not found"])
+
+    @patch.object(novncd_mod, "get_connection_infos")
+    def test_a_fault_of_the_panel_is_logged_with_its_traceback_without_secrets(self, mock_get_info):
+        try:
+            raise RuntimeError("password=review-dummy-secret")
+        except RuntimeError as cause:
+            mock_get_info.side_effect = OSError("console setup failed")
+            mock_get_info.side_effect.__cause__ = cause
+        handler = self.ConsoleClient()
+        handler.path = "/novncd/?token=1-uuid"
+        with self.assertLogs(level="WARNING") as logs:
+            handler._new_client(socket_factory=MagicMock())
+        self.assertIn("Traceback", logs.output[0])
+        self.assertIn("password=***", logs.output[0])
+        self.assertNotIn("review-dummy-secret", logs.output[0])
+
     @patch.object(novncd_mod, "get_connection_infos")
     def test_a_cookie_does_not_choose_the_console(self, mock_get_info):
         # another tab's console in a cookie: the URL's own token is used