Fix rqt controller manager

[saikishor]

Fixes #1223

Before:

Traceback (most recent call last):
  File "/workspaces/ros2_baustelle_ws/build/rqt_controller_manager/rqt_controller_manager/controller_manager.py", line 153, in _update_controllers
    controllers = self._list_controllers()
  File "/workspaces/ros2_baustelle_ws/build/rqt_controller_manager/rqt_controller_manager/controller_manager.py", line 171, in _list_controllers
    controllers = list_controllers(self._node, self._cm_name).controller
  File "/workspaces/ros2_baustelle_ws/install/controller_manager/local/lib/python3.10/dist-packages/controller_manager/controller_manager_services.py", line 49, in list_controllers
    return service_caller(node, f'{controller_manager_name}/list_controllers',
  File "/workspaces/ros2_baustelle_ws/install/controller_manager/local/lib/python3.10/dist-packages/controller_manager/controller_manager_services.py", line 29, in service_caller
    raise RuntimeError(f'Could not contact service {service_name}')
RuntimeError: Could not contact service /controller_manager/list_controllers

Now, instead of raising an exception and closing, it will clear the window and then connects to the server when it is available again

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (64c9e2a) 47.89% compared to head (e7ed02d) 47.89%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1273   +/-   ##
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  Coverage   47.89%   47.89%           
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  Files          41       41           
  Lines        3451     3451           
  Branches     1876     1876           
=======================================
  Hits         1653     1653           
  Misses        444      444           
  Partials     1354     1354           

Flag	Coverage Δ
unittests	47.89% <ø> (ø)

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[bmagyar]

Fantastic!

[christophfroehlich]

Works great, thanks :)