MAASServerTestCase.setUp() is overly broad

[Gavin Panella]

There's code in MAASServerTestCase.setUp() that really ought to moved
into fixtures or be done for specific test cases, perhaps with
setUpClass(). It really does not belong here.

The current offenders:

  # This patch prevents communication with a non-existent cluster
  # controller when fetching power types.
  static_params = (
      provisioningserver.power_schema.JSON_POWER_TYPE_PARAMETERS)
  self.patch(
      power_parameters,
      'get_all_power_types_from_clusters').return_value = static_params

  # Disconnect the monitor cancellation as it's triggered by a signal.
  # Avoid circular imports.
  from maasserver import monitor_connect
  self.patch(monitor_connect, 'MONITOR_CANCEL_CONNECT', False)

  # Disconnect the status transition event to speed up tests.
  # Avoid circular imports.
  from maasserver import event_connect
  self.patch(event_connect, 'STATE_TRANSITION_EVENT_CONNECT', False)