Corrected information that Sensor.is_listening is (currently) a method

[Daraan]

Description

carla.Sensor.is_listening is defined twice (since #6013) the <0.9.14 property is overwritten with a method; can also be seen in the Docs

This PR removes the overwritten property and updates the doc, keeping the 0.9.14+ method version in tact.

https://github.com/carla-simulator/carla/blob/f22d49d784c24eb77a4b832c5232ef50880b5dd5/PythonAPI/carla/source/libcarla/Sensor.cpp#L29-L31

Where has this been tested?

• Platform(s): Ubuntu 22.04
• Python version(s): 3.7 and 3.10
• Unreal Engine version(s): 4.26
• all checks green

Possible Drawbacks

None.

Future work, make it a property again?

I at least would prefer function names like is_listening as a property. On one side, it would break the current 0.9.14/15 compatibility, on the other it would restore the one from <0.9.13 which still is found in code more often. So we might want to shift the three Sensor.is_... functions to a property.