Remove first handler update as queue update is blocked

[lboorman]

The queue length for the subscriber isn't set as the code doesn't get that far after setting the throttle rate and returning the updated handler.

Public API Changes
None

Description
Remove the first handle update. The throttle and queue_length stacked methods are still added correctly when updating the second queue_length option, via the conditional statements.

Testing

Without the change: ROS2 debug messages were added (node handle passed to lower classes) and showed the queue_length wasn't being set in `subscription_modifiers.py/MessageHandler.set_queue_length()

With the change added: Ran the bridge with a ROS image publisher and a bridged image subscriber. Setting the throttling rate, changed the image update rates, with or without queue length. Then setting slow throttling (300ms) with a large existing queue showed a long delay in image updates. With a very small queue, throttling effects were immediate.

None

[sea-bass]

Looking at the code, I can't tell why this wouldn't have worked in the first place...

But based on the tests, I guess this helps? And it doesn't look like it will hurt anyhow.