Crash if timeout of polkit password prompt runs out

[buhtz]

Describe the problem, feature or ask a question:

1. Setup a profile with udev scheduling.
2. Click OK and the polkit password prompt will appear.
3. Do nothing. No password. No OK. No Cancel. Just wait.
4. After the dialogs timeout passed BIT crashes.

Traceback (most recent call last):
  File "/usr/share/backintime/qt/manageprofiles/__init__.py", line 379, in accept
    if self.validate():
       ~~~~~~~~~~~~~^^
  File "/usr/share/backintime/qt/manageprofiles/__init__.py", line 346, in validate
    self.config.setup_automation()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/share/backintime/common/config.py", line 1491, in setup_automation
    self._setup_event_based_automation()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/usr/share/backintime/common/config.py", line 1527, in _setup_event_based_automation
    if self.setupUdev.isReady and self.setupUdev.save():
                                  ~~~~~~~~~~~~~~~~~~~^^
  File "/usr/share/backintime/common/tools.py", line 2199, in save
    raise err
  File "/usr/share/backintime/common/tools.py", line 2191, in save
    return self.iface.save()
           ~~~~~~~~~~~~~~~^^
  File "/usr/lib/python3/dist-packages/dbus/proxies.py", line 141, in __call__
    return self._connection.call_blocking(self._named_service,
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^
                                          self._object_path,
                                          ^^^^^^^^^^^^^^^^^^
    ...<3 lines>...
                                          args,
                                          ^^^^^
                                          **keywords)
                                          ^^^^^^^^^^^
  File "/usr/lib/python3/dist-packages/dbus/connection.py", line 696, in call_blocking
    reply_message = self.send_message_with_reply_and_block(
        message, timeout)
dbus.exceptions.DBusException: org.freedesktop.DBus.Error.NoReply: Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.
Aborted

[Ajeem-git]

I opened a PR for this here: #2456

The change handles the D-Bus NoReply timeout from the polkit prompt as a non-fatal timeout condition, then reports it to the user instead of crashing the dialog.

I traced the exception path from the issue traceback and verified the updated files compile locally.