I am running this as you want configured, but also with double aruco markers.
Try running the sim_vehicle first and wait a bit, then in a 2nd terminal run gazebo and it should connect.
…/Tools/autotest/sim_vehicle.py -f gazebo-iris
roslaunch gazebo_ros iris_world.launch
or in my case:
roslaunch gazebo_ros iris_world.launch world_name:=“2_arucos.world”
Also note: https://community.dojofordrones.com/t/full-gz-sim-on-22-04-lts/805/6